<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2025 Workiva-->
<!--r:294e7d9e-b79b-483a-8ef5-7f8a92b73359,g:92036178-95e3-482b-9133-10804d35b565-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
  <link:roleRef roleURI="http://www.nextdoor.com/role/Cover" xlink:type="simple" xlink:href="nxdr-20250930.xsd#Cover"/>
  <link:definitionLink xlink:role="http://www.nextdoor.com/role/Cover" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentInformationLineItems_10c1f984-f3d9-4547-ac86-c3de86ad6a3b" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_DocumentInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentInformationTable_cb6f6404-9523-4426-ace7-ad377193f749" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_DocumentInformationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_dei_DocumentInformationLineItems_10c1f984-f3d9-4547-ac86-c3de86ad6a3b" xlink:to="loc_dei_DocumentInformationTable_cb6f6404-9523-4426-ace7-ad377193f749" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_0184e78f-b914-4ca1-830c-0fceb0360dd1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_dei_DocumentInformationTable_cb6f6404-9523-4426-ace7-ad377193f749" xlink:to="loc_us-gaap_StatementClassOfStockAxis_0184e78f-b914-4ca1-830c-0fceb0360dd1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_0184e78f-b914-4ca1-830c-0fceb0360dd1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_0184e78f-b914-4ca1-830c-0fceb0360dd1" xlink:to="loc_us-gaap_ClassOfStockDomain_0184e78f-b914-4ca1-830c-0fceb0360dd1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_c0d30b00-6775-4c37-96ac-1dab943bc24a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_0184e78f-b914-4ca1-830c-0fceb0360dd1" xlink:to="loc_us-gaap_ClassOfStockDomain_c0d30b00-6775-4c37-96ac-1dab943bc24a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_f26a9d6a-08bd-4715-8278-6dc5915611b4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_c0d30b00-6775-4c37-96ac-1dab943bc24a" xlink:to="loc_us-gaap_CommonClassAMember_f26a9d6a-08bd-4715-8278-6dc5915611b4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassBMember_57aef305-8854-4a53-8763-83f6791735fb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonClassBMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_c0d30b00-6775-4c37-96ac-1dab943bc24a" xlink:to="loc_us-gaap_CommonClassBMember_57aef305-8854-4a53-8763-83f6791735fb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentType_6a402881-e3c8-495e-aa89-283715a9843f" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_DocumentType"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_10c1f984-f3d9-4547-ac86-c3de86ad6a3b" xlink:to="loc_dei_DocumentType_6a402881-e3c8-495e-aa89-283715a9843f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentQuarterlyReport_6ed09f50-818f-4b35-9add-b932c14a4963" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_DocumentQuarterlyReport"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_10c1f984-f3d9-4547-ac86-c3de86ad6a3b" xlink:to="loc_dei_DocumentQuarterlyReport_6ed09f50-818f-4b35-9add-b932c14a4963" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentPeriodEndDate_30c90d75-c987-4a92-acb3-b4a893742e1c" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_DocumentPeriodEndDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_10c1f984-f3d9-4547-ac86-c3de86ad6a3b" xlink:to="loc_dei_DocumentPeriodEndDate_30c90d75-c987-4a92-acb3-b4a893742e1c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentTransitionReport_f58c9419-2f3d-49d8-b66d-88298111cf4c" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_DocumentTransitionReport"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_10c1f984-f3d9-4547-ac86-c3de86ad6a3b" xlink:to="loc_dei_DocumentTransitionReport_f58c9419-2f3d-49d8-b66d-88298111cf4c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityFileNumber_cfdbb2c8-d6d4-4a2c-abc5-741681c9562b" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityFileNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_10c1f984-f3d9-4547-ac86-c3de86ad6a3b" xlink:to="loc_dei_EntityFileNumber_cfdbb2c8-d6d4-4a2c-abc5-741681c9562b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityRegistrantName_82ec994b-9489-4895-a384-f678a0ec3136" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityRegistrantName"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_10c1f984-f3d9-4547-ac86-c3de86ad6a3b" xlink:to="loc_dei_EntityRegistrantName_82ec994b-9489-4895-a384-f678a0ec3136" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityIncorporationStateCountryCode_45cb2ece-af51-46d7-8710-0094003d0398" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityIncorporationStateCountryCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_10c1f984-f3d9-4547-ac86-c3de86ad6a3b" xlink:to="loc_dei_EntityIncorporationStateCountryCode_45cb2ece-af51-46d7-8710-0094003d0398" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityTaxIdentificationNumber_2f9c206d-8a4f-4fd3-ad80-c10f0559a498" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityTaxIdentificationNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_10c1f984-f3d9-4547-ac86-c3de86ad6a3b" xlink:to="loc_dei_EntityTaxIdentificationNumber_2f9c206d-8a4f-4fd3-ad80-c10f0559a498" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressAddressLine1_9b7279f3-5b24-47eb-b2cd-9a570a019289" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityAddressAddressLine1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_10c1f984-f3d9-4547-ac86-c3de86ad6a3b" xlink:to="loc_dei_EntityAddressAddressLine1_9b7279f3-5b24-47eb-b2cd-9a570a019289" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressCityOrTown_7b9f8ff1-b37e-4188-9c00-c1627f1f2ef3" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityAddressCityOrTown"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_10c1f984-f3d9-4547-ac86-c3de86ad6a3b" xlink:to="loc_dei_EntityAddressCityOrTown_7b9f8ff1-b37e-4188-9c00-c1627f1f2ef3" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressStateOrProvince_d6091031-5d58-4878-90eb-688c42d94172" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityAddressStateOrProvince"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_10c1f984-f3d9-4547-ac86-c3de86ad6a3b" xlink:to="loc_dei_EntityAddressStateOrProvince_d6091031-5d58-4878-90eb-688c42d94172" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressPostalZipCode_a8847a4d-ae93-43af-90ad-9c24d62430ee" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityAddressPostalZipCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_10c1f984-f3d9-4547-ac86-c3de86ad6a3b" xlink:to="loc_dei_EntityAddressPostalZipCode_a8847a4d-ae93-43af-90ad-9c24d62430ee" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_CityAreaCode_20fdb26d-0bac-4470-8a8e-dc8da4a47337" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_CityAreaCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_10c1f984-f3d9-4547-ac86-c3de86ad6a3b" xlink:to="loc_dei_CityAreaCode_20fdb26d-0bac-4470-8a8e-dc8da4a47337" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LocalPhoneNumber_a67fdd46-91ea-4aeb-97ac-c4d5fa02bfc2" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_LocalPhoneNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_10c1f984-f3d9-4547-ac86-c3de86ad6a3b" xlink:to="loc_dei_LocalPhoneNumber_a67fdd46-91ea-4aeb-97ac-c4d5fa02bfc2" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_Security12bTitle_0c94078d-a049-4d51-a7c5-566d3b92ce7b" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_Security12bTitle"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_10c1f984-f3d9-4547-ac86-c3de86ad6a3b" xlink:to="loc_dei_Security12bTitle_0c94078d-a049-4d51-a7c5-566d3b92ce7b" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_TradingSymbol_8b16bd6f-4a5b-4d73-9240-c84f8c61ba93" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_TradingSymbol"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_10c1f984-f3d9-4547-ac86-c3de86ad6a3b" xlink:to="loc_dei_TradingSymbol_8b16bd6f-4a5b-4d73-9240-c84f8c61ba93" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_SecurityExchangeName_7f2cb762-d6f0-4f44-852e-014b14b70408" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_SecurityExchangeName"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_10c1f984-f3d9-4547-ac86-c3de86ad6a3b" xlink:to="loc_dei_SecurityExchangeName_7f2cb762-d6f0-4f44-852e-014b14b70408" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCurrentReportingStatus_99e305e5-3e72-471e-9deb-9af62d193857" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityCurrentReportingStatus"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_10c1f984-f3d9-4547-ac86-c3de86ad6a3b" xlink:to="loc_dei_EntityCurrentReportingStatus_99e305e5-3e72-471e-9deb-9af62d193857" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityInteractiveDataCurrent_52dec8a2-37b9-476e-b3d0-97ead8ad6cfb" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityInteractiveDataCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_10c1f984-f3d9-4547-ac86-c3de86ad6a3b" xlink:to="loc_dei_EntityInteractiveDataCurrent_52dec8a2-37b9-476e-b3d0-97ead8ad6cfb" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityFilerCategory_544ab0bd-9b0d-4e17-a2b5-3e841043222f" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityFilerCategory"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_10c1f984-f3d9-4547-ac86-c3de86ad6a3b" xlink:to="loc_dei_EntityFilerCategory_544ab0bd-9b0d-4e17-a2b5-3e841043222f" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntitySmallBusiness_e3ef06a7-9880-4398-9fdc-0965ac2fd430" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntitySmallBusiness"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_10c1f984-f3d9-4547-ac86-c3de86ad6a3b" xlink:to="loc_dei_EntitySmallBusiness_e3ef06a7-9880-4398-9fdc-0965ac2fd430" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityEmergingGrowthCompany_a0d317e6-64e4-46d7-999f-9cae68944279" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityEmergingGrowthCompany"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_10c1f984-f3d9-4547-ac86-c3de86ad6a3b" xlink:to="loc_dei_EntityEmergingGrowthCompany_a0d317e6-64e4-46d7-999f-9cae68944279" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityShellCompany_0de21ed8-a598-4182-8f52-a0399aaf68e9" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityShellCompany"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_10c1f984-f3d9-4547-ac86-c3de86ad6a3b" xlink:to="loc_dei_EntityShellCompany_0de21ed8-a598-4182-8f52-a0399aaf68e9" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCommonStockSharesOutstanding_694c05c5-4989-4b11-8085-c2fca9b83da2" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityCommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_10c1f984-f3d9-4547-ac86-c3de86ad6a3b" xlink:to="loc_dei_EntityCommonStockSharesOutstanding_694c05c5-4989-4b11-8085-c2fca9b83da2" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_AmendmentFlag_2dde33b5-2f57-44a5-8de7-24dce97c03ea" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_AmendmentFlag"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_10c1f984-f3d9-4547-ac86-c3de86ad6a3b" xlink:to="loc_dei_AmendmentFlag_2dde33b5-2f57-44a5-8de7-24dce97c03ea" xlink:type="arc" order="24"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCentralIndexKey_3989e87d-2aa5-4abf-927d-405585a2da21" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityCentralIndexKey"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_10c1f984-f3d9-4547-ac86-c3de86ad6a3b" xlink:to="loc_dei_EntityCentralIndexKey_3989e87d-2aa5-4abf-927d-405585a2da21" xlink:type="arc" order="25"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentFiscalYearFocus_329435d7-9e6d-4c29-9bd4-96e8bcbc2d64" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_DocumentFiscalYearFocus"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_10c1f984-f3d9-4547-ac86-c3de86ad6a3b" xlink:to="loc_dei_DocumentFiscalYearFocus_329435d7-9e6d-4c29-9bd4-96e8bcbc2d64" xlink:type="arc" order="26"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentFiscalPeriodFocus_8d10f332-035f-463e-ad57-dd98706e66ba" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_DocumentFiscalPeriodFocus"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_10c1f984-f3d9-4547-ac86-c3de86ad6a3b" xlink:to="loc_dei_DocumentFiscalPeriodFocus_8d10f332-035f-463e-ad57-dd98706e66ba" xlink:type="arc" order="27"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_CurrentFiscalYearEndDate_e4aab8ab-6f67-443d-9470-5f23e3a51f72" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_CurrentFiscalYearEndDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_10c1f984-f3d9-4547-ac86-c3de86ad6a3b" xlink:to="loc_dei_CurrentFiscalYearEndDate_e4aab8ab-6f67-443d-9470-5f23e3a51f72" xlink:type="arc" order="28"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nextdoor.com/role/CONDENSEDCONSOLIDATEDBALANCESHEETS" xlink:type="simple" xlink:href="nxdr-20250930.xsd#CONDENSEDCONSOLIDATEDBALANCESHEETS"/>
  <link:definitionLink xlink:role="http://www.nextdoor.com/role/CONDENSEDCONSOLIDATEDBALANCESHEETS" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_c68d0477-dc49-4834-a2ac-d02747bd7152" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_38b8a36a-9a4c-4fba-af16-d29ba705b6e2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_c68d0477-dc49-4834-a2ac-d02747bd7152" xlink:to="loc_us-gaap_StatementTable_38b8a36a-9a4c-4fba-af16-d29ba705b6e2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_0443ef1c-368f-41c9-8626-89f7c56031c9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_38b8a36a-9a4c-4fba-af16-d29ba705b6e2" xlink:to="loc_us-gaap_StatementClassOfStockAxis_0443ef1c-368f-41c9-8626-89f7c56031c9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_0443ef1c-368f-41c9-8626-89f7c56031c9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_0443ef1c-368f-41c9-8626-89f7c56031c9" xlink:to="loc_us-gaap_ClassOfStockDomain_0443ef1c-368f-41c9-8626-89f7c56031c9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_08bf5fee-6304-4d8e-9129-448326022002" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_0443ef1c-368f-41c9-8626-89f7c56031c9" xlink:to="loc_us-gaap_ClassOfStockDomain_08bf5fee-6304-4d8e-9129-448326022002" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_d3f5423f-15d3-4229-91ef-acd39e1a08d9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_08bf5fee-6304-4d8e-9129-448326022002" xlink:to="loc_us-gaap_CommonClassAMember_d3f5423f-15d3-4229-91ef-acd39e1a08d9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassBMember_6773e09b-5b5e-44e1-868a-afdf6738aeac" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonClassBMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_08bf5fee-6304-4d8e-9129-448326022002" xlink:to="loc_us-gaap_CommonClassBMember_6773e09b-5b5e-44e1-868a-afdf6738aeac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsAbstract_1cfe77e3-fac6-4847-9ce5-f47cb950b33f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_c68d0477-dc49-4834-a2ac-d02747bd7152" xlink:to="loc_us-gaap_AssetsAbstract_1cfe77e3-fac6-4847-9ce5-f47cb950b33f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrentAbstract_8a2ef92d-f2b0-4cee-818c-f315b278acc3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsCurrentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_1cfe77e3-fac6-4847-9ce5-f47cb950b33f" xlink:to="loc_us-gaap_AssetsCurrentAbstract_8a2ef92d-f2b0-4cee-818c-f315b278acc3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_1a203865-fc58-45c8-9b4d-c16a2d6f0fdb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_8a2ef92d-f2b0-4cee-818c-f315b278acc3" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_1a203865-fc58-45c8-9b4d-c16a2d6f0fdb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecuritiesCurrent_f0a86588-2e58-481a-a4c7-04fa2e4d0187" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecuritiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_8a2ef92d-f2b0-4cee-818c-f315b278acc3" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecuritiesCurrent_f0a86588-2e58-481a-a4c7-04fa2e4d0187" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableNetCurrent_c3fb1eaa-a578-423b-9174-489645daf9e8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccountsReceivableNetCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_8a2ef92d-f2b0-4cee-818c-f315b278acc3" xlink:to="loc_us-gaap_AccountsReceivableNetCurrent_c3fb1eaa-a578-423b-9174-489645daf9e8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_9ec46946-4497-4956-ae91-157cfcfc132f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PrepaidExpenseAndOtherAssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_8a2ef92d-f2b0-4cee-818c-f315b278acc3" xlink:to="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_9ec46946-4497-4956-ae91-157cfcfc132f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrent_6edef8f5-ad25-44b4-abad-61f28be7bb83" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_8a2ef92d-f2b0-4cee-818c-f315b278acc3" xlink:to="loc_us-gaap_AssetsCurrent_6edef8f5-ad25-44b4-abad-61f28be7bb83" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashNoncurrent_9310867b-fe18-4119-b56b-c834512db118" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestrictedCashNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_1cfe77e3-fac6-4847-9ce5-f47cb950b33f" xlink:to="loc_us-gaap_RestrictedCashNoncurrent_9310867b-fe18-4119-b56b-c834512db118" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_710d6268-a6da-432f-b9b9-56ddcbc9d567" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_1cfe77e3-fac6-4847-9ce5-f47cb950b33f" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_710d6268-a6da-432f-b9b9-56ddcbc9d567" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset_0ddfc7d4-4711-44c0-83c2-71481f0fd990" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLeaseRightOfUseAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_1cfe77e3-fac6-4847-9ce5-f47cb950b33f" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAsset_0ddfc7d4-4711-44c0-83c2-71481f0fd990" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_788debae-e0f8-4ddd-b0d2-ff58ad1545e3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_1cfe77e3-fac6-4847-9ce5-f47cb950b33f" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_788debae-e0f8-4ddd-b0d2-ff58ad1545e3" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_cb59de88-f2c6-4397-b9b0-d3e10acfa522" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_1cfe77e3-fac6-4847-9ce5-f47cb950b33f" xlink:to="loc_us-gaap_Goodwill_cb59de88-f2c6-4397-b9b0-d3e10acfa522" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsNoncurrent_62485ab6-2d64-4196-b935-17ba390f8196" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherAssetsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_1cfe77e3-fac6-4847-9ce5-f47cb950b33f" xlink:to="loc_us-gaap_OtherAssetsNoncurrent_62485ab6-2d64-4196-b935-17ba390f8196" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_747a6939-0838-4943-bccb-93c30cdaca12" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_1cfe77e3-fac6-4847-9ce5-f47cb950b33f" xlink:to="loc_us-gaap_Assets_747a6939-0838-4943-bccb-93c30cdaca12" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_7a4371ac-777b-4c57-b1d2-68b0c4273ee9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesAndStockholdersEquityAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_c68d0477-dc49-4834-a2ac-d02747bd7152" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_7a4371ac-777b-4c57-b1d2-68b0c4273ee9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrentAbstract_fb918caf-2c4a-4300-841e-c2fa6fe25486" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesCurrentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_7a4371ac-777b-4c57-b1d2-68b0c4273ee9" xlink:to="loc_us-gaap_LiabilitiesCurrentAbstract_fb918caf-2c4a-4300-841e-c2fa6fe25486" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableCurrent_0ef4e414-5736-4010-9a69-d77b2ce3ec86" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccountsPayableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_fb918caf-2c4a-4300-841e-c2fa6fe25486" xlink:to="loc_us-gaap_AccountsPayableCurrent_0ef4e414-5736-4010-9a69-d77b2ce3ec86" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityCurrent_b9add1a1-1737-4ec1-b4ce-3116ee460846" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLeaseLiabilityCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_fb918caf-2c4a-4300-841e-c2fa6fe25486" xlink:to="loc_us-gaap_OperatingLeaseLiabilityCurrent_b9add1a1-1737-4ec1-b4ce-3116ee460846" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedLiabilitiesCurrent_ae1666b5-515a-4573-9c3b-b310a175567c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccruedLiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_fb918caf-2c4a-4300-841e-c2fa6fe25486" xlink:to="loc_us-gaap_AccruedLiabilitiesCurrent_ae1666b5-515a-4573-9c3b-b310a175567c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrent_d3724fd7-5f7e-4fd8-9db7-3ff428e7bd4a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_fb918caf-2c4a-4300-841e-c2fa6fe25486" xlink:to="loc_us-gaap_LiabilitiesCurrent_d3724fd7-5f7e-4fd8-9db7-3ff428e7bd4a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_812898c6-42a3-42aa-903c-455f3aba53e7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLeaseLiabilityNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_7a4371ac-777b-4c57-b1d2-68b0c4273ee9" xlink:to="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_812898c6-42a3-42aa-903c-455f3aba53e7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilitiesNoncurrent_e1153b5f-3095-4dc9-8191-c3a117b85dfd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherLiabilitiesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_7a4371ac-777b-4c57-b1d2-68b0c4273ee9" xlink:to="loc_us-gaap_OtherLiabilitiesNoncurrent_e1153b5f-3095-4dc9-8191-c3a117b85dfd" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Liabilities_ba9a5026-ce8d-469d-8407-2b5218aeed04" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Liabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_7a4371ac-777b-4c57-b1d2-68b0c4273ee9" xlink:to="loc_us-gaap_Liabilities_ba9a5026-ce8d-469d-8407-2b5218aeed04" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommitmentsAndContingencies_825f2faf-1bdc-49ae-8e66-89d7305ec92e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommitmentsAndContingencies"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_7a4371ac-777b-4c57-b1d2-68b0c4273ee9" xlink:to="loc_us-gaap_CommitmentsAndContingencies_825f2faf-1bdc-49ae-8e66-89d7305ec92e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityAbstract_5f46dff6-ef5f-4e26-a794-3406aef0ee3a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquityAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_7a4371ac-777b-4c57-b1d2-68b0c4273ee9" xlink:to="loc_us-gaap_StockholdersEquityAbstract_5f46dff6-ef5f-4e26-a794-3406aef0ee3a" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockValue_300da4ed-dab3-4ad6-8be1-1a5248e91e24" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_5f46dff6-ef5f-4e26-a794-3406aef0ee3a" xlink:to="loc_us-gaap_CommonStockValue_300da4ed-dab3-4ad6-8be1-1a5248e91e24" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapital_5e37ca1d-9eb4-40f0-bf6b-d5a3e984ba84" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalPaidInCapital"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_5f46dff6-ef5f-4e26-a794-3406aef0ee3a" xlink:to="loc_us-gaap_AdditionalPaidInCapital_5e37ca1d-9eb4-40f0-bf6b-d5a3e984ba84" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_80e86d70-4835-4ce9-b084-92a45025cae9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_5f46dff6-ef5f-4e26-a794-3406aef0ee3a" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_80e86d70-4835-4ce9-b084-92a45025cae9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_9fee8a71-582e-4677-886a-c1fb71738579" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetainedEarningsAccumulatedDeficit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_5f46dff6-ef5f-4e26-a794-3406aef0ee3a" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_9fee8a71-582e-4677-886a-c1fb71738579" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_a2ce118d-662c-4433-9c77-97f28cbe4bbc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_5f46dff6-ef5f-4e26-a794-3406aef0ee3a" xlink:to="loc_us-gaap_StockholdersEquity_a2ce118d-662c-4433-9c77-97f28cbe4bbc" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity_61232010-5b87-45a1-a5af-24b9939f3653" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesAndStockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_7a4371ac-777b-4c57-b1d2-68b0c4273ee9" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquity_61232010-5b87-45a1-a5af-24b9939f3653" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nextdoor.com/role/CONDENSEDCONSOLIDATEDBALANCESHEETSParenthetical" xlink:type="simple" xlink:href="nxdr-20250930.xsd#CONDENSEDCONSOLIDATEDBALANCESHEETSParenthetical"/>
  <link:definitionLink xlink:role="http://www.nextdoor.com/role/CONDENSEDCONSOLIDATEDBALANCESHEETSParenthetical" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_90ddf0c6-4216-4e33-a6b6-33cfc7181bf8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_61783c84-0d80-471f-8370-2f7edc19d06b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_90ddf0c6-4216-4e33-a6b6-33cfc7181bf8" xlink:to="loc_us-gaap_StatementTable_61783c84-0d80-471f-8370-2f7edc19d06b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_99022fe4-d4ac-4042-a832-eff275858c22" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_61783c84-0d80-471f-8370-2f7edc19d06b" xlink:to="loc_us-gaap_StatementClassOfStockAxis_99022fe4-d4ac-4042-a832-eff275858c22" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_99022fe4-d4ac-4042-a832-eff275858c22_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_99022fe4-d4ac-4042-a832-eff275858c22" xlink:to="loc_us-gaap_ClassOfStockDomain_99022fe4-d4ac-4042-a832-eff275858c22_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_46100d7c-6f0c-4fba-a0fa-4b1e0e1e5460" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_99022fe4-d4ac-4042-a832-eff275858c22" xlink:to="loc_us-gaap_ClassOfStockDomain_46100d7c-6f0c-4fba-a0fa-4b1e0e1e5460" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_004a3ca0-0829-4c50-9c98-8c1a783055c8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_46100d7c-6f0c-4fba-a0fa-4b1e0e1e5460" xlink:to="loc_us-gaap_CommonClassAMember_004a3ca0-0829-4c50-9c98-8c1a783055c8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassBMember_da18479e-6885-4827-ae87-46065ffa4ee9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonClassBMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_46100d7c-6f0c-4fba-a0fa-4b1e0e1e5460" xlink:to="loc_us-gaap_CommonClassBMember_da18479e-6885-4827-ae87-46065ffa4ee9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_d004c426-5cb3-4710-a65c-a9d9aaaf4bcd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_90ddf0c6-4216-4e33-a6b6-33cfc7181bf8" xlink:to="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_d004c426-5cb3-4710-a65c-a9d9aaaf4bcd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockParOrStatedValuePerShare_ec62f582-9a61-41fd-a8f6-db8e838fbc66" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockParOrStatedValuePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_90ddf0c6-4216-4e33-a6b6-33cfc7181bf8" xlink:to="loc_us-gaap_CommonStockParOrStatedValuePerShare_ec62f582-9a61-41fd-a8f6-db8e838fbc66" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesAuthorized_d4185f5f-45e6-410d-b109-118cbd9690ec" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_90ddf0c6-4216-4e33-a6b6-33cfc7181bf8" xlink:to="loc_us-gaap_CommonStockSharesAuthorized_d4185f5f-45e6-410d-b109-118cbd9690ec" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesIssued_6fc8f4b1-7793-48b5-a871-de1ebf9eb929" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_90ddf0c6-4216-4e33-a6b6-33cfc7181bf8" xlink:to="loc_us-gaap_CommonStockSharesIssued_6fc8f4b1-7793-48b5-a871-de1ebf9eb929" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_c69e477c-6fad-4fd7-a547-d317e0a7ad43" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_90ddf0c6-4216-4e33-a6b6-33cfc7181bf8" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_c69e477c-6fad-4fd7-a547-d317e0a7ad43" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nextdoor.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITY" xlink:type="simple" xlink:href="nxdr-20250930.xsd#CONDENSEDCONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITY"/>
  <link:definitionLink xlink:role="http://www.nextdoor.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITY" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_bbcb19ec-8d7e-4959-819e-08e8c1c749ea" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_71246d3a-43cf-4c91-ba29-6539f10dbc64" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_bbcb19ec-8d7e-4959-819e-08e8c1c749ea" xlink:to="loc_us-gaap_StatementTable_71246d3a-43cf-4c91-ba29-6539f10dbc64" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_e5393a3e-9942-4d15-b2a6-db50e3c2a142" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_71246d3a-43cf-4c91-ba29-6539f10dbc64" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_e5393a3e-9942-4d15-b2a6-db50e3c2a142" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_e5393a3e-9942-4d15-b2a6-db50e3c2a142_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_e5393a3e-9942-4d15-b2a6-db50e3c2a142" xlink:to="loc_us-gaap_EquityComponentDomain_e5393a3e-9942-4d15-b2a6-db50e3c2a142_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_58092ace-0fbc-4e00-b543-584288fe8e9b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_e5393a3e-9942-4d15-b2a6-db50e3c2a142" xlink:to="loc_us-gaap_EquityComponentDomain_58092ace-0fbc-4e00-b543-584288fe8e9b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_65ae4520-0f43-418f-8844-0078dd0c30bc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_58092ace-0fbc-4e00-b543-584288fe8e9b" xlink:to="loc_us-gaap_CommonStockMember_65ae4520-0f43-418f-8844-0078dd0c30bc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_7dbaada4-ab73-40f1-8503-5aa798827f81" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_58092ace-0fbc-4e00-b543-584288fe8e9b" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_7dbaada4-ab73-40f1-8503-5aa798827f81" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_013ccaef-3c74-4793-8c8a-627fcce948fd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_58092ace-0fbc-4e00-b543-584288fe8e9b" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_013ccaef-3c74-4793-8c8a-627fcce948fd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_e300e195-ab70-40c8-870b-2d304305912e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_58092ace-0fbc-4e00-b543-584288fe8e9b" xlink:to="loc_us-gaap_RetainedEarningsMember_e300e195-ab70-40c8-870b-2d304305912e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_a809daf5-8cac-4e1b-acf3-0ec299870b97" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_71246d3a-43cf-4c91-ba29-6539f10dbc64" xlink:to="loc_us-gaap_StatementClassOfStockAxis_a809daf5-8cac-4e1b-acf3-0ec299870b97" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_a809daf5-8cac-4e1b-acf3-0ec299870b97_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_a809daf5-8cac-4e1b-acf3-0ec299870b97" xlink:to="loc_us-gaap_ClassOfStockDomain_a809daf5-8cac-4e1b-acf3-0ec299870b97_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_edf7e034-8bcf-452e-b5e2-16745519ff2d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_a809daf5-8cac-4e1b-acf3-0ec299870b97" xlink:to="loc_us-gaap_ClassOfStockDomain_edf7e034-8bcf-452e-b5e2-16745519ff2d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_7eacb0c1-2871-4499-8654-b3ec8acac459" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_edf7e034-8bcf-452e-b5e2-16745519ff2d" xlink:to="loc_us-gaap_CommonClassAMember_7eacb0c1-2871-4499-8654-b3ec8acac459" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassBMember_b9970e38-c6c2-42af-8f94-009a00dcc6d4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonClassBMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_edf7e034-8bcf-452e-b5e2-16745519ff2d" xlink:to="loc_us-gaap_CommonClassBMember_b9970e38-c6c2-42af-8f94-009a00dcc6d4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_4733c9ff-b372-4c5a-8a70-cc3294ac01a2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_bbcb19ec-8d7e-4959-819e-08e8c1c749ea" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_4733c9ff-b372-4c5a-8a70-cc3294ac01a2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_f8fbf3b8-ae2a-485d-92df-d467ce6c1e63" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_4733c9ff-b372-4c5a-8a70-cc3294ac01a2" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_f8fbf3b8-ae2a-485d-92df-d467ce6c1e63" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_8f2d5da3-f73e-4f63-81fd-6cba16969cef" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_4733c9ff-b372-4c5a-8a70-cc3294ac01a2" xlink:to="loc_us-gaap_StockholdersEquity_8f2d5da3-f73e-4f63-81fd-6cba16969cef" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardForfeited_b196269f-8c86-4d2b-9689-b74265595011" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardForfeited"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_4733c9ff-b372-4c5a-8a70-cc3294ac01a2" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardForfeited_b196269f-8c86-4d2b-9689-b74265595011" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_789de466-c80d-4504-b6d6-40700116edf8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_4733c9ff-b372-4c5a-8a70-cc3294ac01a2" xlink:to="loc_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_789de466-c80d-4504-b6d6-40700116edf8" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodShares_2f2e584c-6977-4ec4-b490-8597b0cb9405" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockRepurchasedDuringPeriodShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_4733c9ff-b372-4c5a-8a70-cc3294ac01a2" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodShares_2f2e584c-6977-4ec4-b490-8597b0cb9405" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodValue_299926c1-dab7-4cf7-9fab-62984dc36d68" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockRepurchasedDuringPeriodValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_4733c9ff-b372-4c5a-8a70-cc3294ac01a2" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodValue_299926c1-dab7-4cf7-9fab-62984dc36d68" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_1162cce4-c054-45a1-b98e-e9a8296a6f42" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_4733c9ff-b372-4c5a-8a70-cc3294ac01a2" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_1162cce4-c054-45a1-b98e-e9a8296a6f42" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities_c314740b-c873-48ef-9c0d-3a9f5c77fbd0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_4733c9ff-b372-4c5a-8a70-cc3294ac01a2" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities_c314740b-c873-48ef-9c0d-3a9f5c77fbd0" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_0075a716-6dd1-4437-98cc-140797eef917" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_4733c9ff-b372-4c5a-8a70-cc3294ac01a2" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_0075a716-6dd1-4437-98cc-140797eef917" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_247958fa-a148-4713-a90a-9b8db9000a4b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_4733c9ff-b372-4c5a-8a70-cc3294ac01a2" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_247958fa-a148-4713-a90a-9b8db9000a4b" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_b2f4ada3-5194-481f-ae36-4e303ffb5a92" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_4733c9ff-b372-4c5a-8a70-cc3294ac01a2" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_b2f4ada3-5194-481f-ae36-4e303ffb5a92" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan_d26d003e-3c7d-4ffb-b392-1c29fe573201" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_4733c9ff-b372-4c5a-8a70-cc3294ac01a2" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan_d26d003e-3c7d-4ffb-b392-1c29fe573201" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_33ef8fb1-56d3-4436-b07c-1c5a02f6fa4f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_4733c9ff-b372-4c5a-8a70-cc3294ac01a2" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_33ef8fb1-56d3-4436-b07c-1c5a02f6fa4f" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_00ecc63d-f298-4706-8f3c-3568c3392d18" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_4733c9ff-b372-4c5a-8a70-cc3294ac01a2" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_00ecc63d-f298-4706-8f3c-3568c3392d18" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_2f223de0-6704-4c72-aaab-14178857561b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_4733c9ff-b372-4c5a-8a70-cc3294ac01a2" xlink:to="loc_us-gaap_NetIncomeLoss_2f223de0-6704-4c72-aaab-14178857561b" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_1118e7dc-bf8a-433a-affe-185aa6893fbc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_1195112e-6f27-4eea-acc1-743737aad3b9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nextdoor.com/role/CashEquivalentsandMarketableSecuritiesAmortizedCostUnrealizedGainsandLossesandEstimatedFairValuesDetails" xlink:type="simple" xlink:href="nxdr-20250930.xsd#CashEquivalentsandMarketableSecuritiesAmortizedCostUnrealizedGainsandLossesandEstimatedFairValuesDetails"/>
  <link:definitionLink xlink:role="http://www.nextdoor.com/role/CashEquivalentsandMarketableSecuritiesAmortizedCostUnrealizedGainsandLossesandEstimatedFairValuesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsLineItems_3dd7a930-06cc-4087-87c3-d079a4b2062f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashAndCashEquivalentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfCashAndCashEquivalentsTable_6e8e3f39-b5c1-40fc-b7f0-6e11333b5c24" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfCashAndCashEquivalentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_CashAndCashEquivalentsLineItems_3dd7a930-06cc-4087-87c3-d079a4b2062f" xlink:to="loc_us-gaap_ScheduleOfCashAndCashEquivalentsTable_6e8e3f39-b5c1-40fc-b7f0-6e11333b5c24" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAxis_481abe83-2a96-4b72-9b6d-c33010d6b3ff" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashAndCashEquivalentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCashAndCashEquivalentsTable_6e8e3f39-b5c1-40fc-b7f0-6e11333b5c24" xlink:to="loc_us-gaap_CashAndCashEquivalentsAxis_481abe83-2a96-4b72-9b6d-c33010d6b3ff" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_481abe83-2a96-4b72-9b6d-c33010d6b3ff_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CashAndCashEquivalentsAxis_481abe83-2a96-4b72-9b6d-c33010d6b3ff" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_481abe83-2a96-4b72-9b6d-c33010d6b3ff_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_2531db64-27bc-4e01-8f44-ce3df3c655fe" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CashAndCashEquivalentsAxis_481abe83-2a96-4b72-9b6d-c33010d6b3ff" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_2531db64-27bc-4e01-8f44-ce3df3c655fe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MoneyMarketFundsMember_0621a346-c4d5-475b-9239-8d7af37e4c1d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MoneyMarketFundsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_2531db64-27bc-4e01-8f44-ce3df3c655fe" xlink:to="loc_us-gaap_MoneyMarketFundsMember_0621a346-c4d5-475b-9239-8d7af37e4c1d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateDebtSecuritiesMember_7ce2584b-0637-4a2d-bb52-7cd1a8b7f629" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CorporateDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_2531db64-27bc-4e01-8f44-ce3df3c655fe" xlink:to="loc_us-gaap_CorporateDebtSecuritiesMember_7ce2584b-0637-4a2d-bb52-7cd1a8b7f629" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialPaperMember_737dfb1e-6766-4d0b-a21c-7fc651361414" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommercialPaperMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_2531db64-27bc-4e01-8f44-ce3df3c655fe" xlink:to="loc_us-gaap_CommercialPaperMember_737dfb1e-6766-4d0b-a21c-7fc651361414" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_35fe95e9-0a8d-4480-a2b5-7bd11d40a18d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCashAndCashEquivalentsTable_6e8e3f39-b5c1-40fc-b7f0-6e11333b5c24" xlink:to="loc_us-gaap_FinancialInstrumentAxis_35fe95e9-0a8d-4480-a2b5-7bd11d40a18d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_35fe95e9-0a8d-4480-a2b5-7bd11d40a18d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_35fe95e9-0a8d-4480-a2b5-7bd11d40a18d" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_35fe95e9-0a8d-4480-a2b5-7bd11d40a18d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_4748b0d3-4c54-4b77-aa97-b0e39597f8da" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_35fe95e9-0a8d-4480-a2b5-7bd11d40a18d" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_4748b0d3-4c54-4b77-aa97-b0e39597f8da" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CertificatesOfDepositMember_50d355d0-c5e8-4ea4-8d9c-b08709b675c0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CertificatesOfDepositMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_4748b0d3-4c54-4b77-aa97-b0e39597f8da" xlink:to="loc_us-gaap_CertificatesOfDepositMember_50d355d0-c5e8-4ea4-8d9c-b08709b675c0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialPaperMember_3f33971d-e96f-43b5-a45b-d7f8b2b23f95" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommercialPaperMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_4748b0d3-4c54-4b77-aa97-b0e39597f8da" xlink:to="loc_us-gaap_CommercialPaperMember_3f33971d-e96f-43b5-a45b-d7f8b2b23f95" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateDebtSecuritiesMember_3d545e7c-ee58-423e-86c3-015da0330e95" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CorporateDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_4748b0d3-4c54-4b77-aa97-b0e39597f8da" xlink:to="loc_us-gaap_CorporateDebtSecuritiesMember_3d545e7c-ee58-423e-86c3-015da0330e95" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USTreasurySecuritiesMember_4abec366-7aee-41f0-8d7b-55d51beee8f1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_USTreasurySecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_4748b0d3-4c54-4b77-aa97-b0e39597f8da" xlink:to="loc_us-gaap_USTreasurySecuritiesMember_4abec366-7aee-41f0-8d7b-55d51beee8f1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetBackedSecuritiesMember_cb625f78-3e2c-4a49-bef0-56cd2df7d4f4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_4748b0d3-4c54-4b77-aa97-b0e39597f8da" xlink:to="loc_us-gaap_AssetBackedSecuritiesMember_cb625f78-3e2c-4a49-bef0-56cd2df7d4f4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashEquivalentsAtCarryingValueAbstract_82e173c2-5795-4da5-afa4-2f49b1474aaa" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashEquivalentsAtCarryingValueAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashAndCashEquivalentsLineItems_3dd7a930-06cc-4087-87c3-d079a4b2062f" xlink:to="loc_us-gaap_CashEquivalentsAtCarryingValueAbstract_82e173c2-5795-4da5-afa4-2f49b1474aaa" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashEquivalentsAtCarryingValue_7cc17a8c-7efa-4755-b116-b51ae3ea0331" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashEquivalentsAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashEquivalentsAtCarryingValueAbstract_82e173c2-5795-4da5-afa4-2f49b1474aaa" xlink:to="loc_us-gaap_CashEquivalentsAtCarryingValue_7cc17a8c-7efa-4755-b116-b51ae3ea0331" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nxdr_CashAndCashEquivalentsUnrealizedGain_7243327b-cf3a-4540-b88b-2aa0ef7e3408" xlink:href="nxdr-20250930.xsd#nxdr_CashAndCashEquivalentsUnrealizedGain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashEquivalentsAtCarryingValueAbstract_82e173c2-5795-4da5-afa4-2f49b1474aaa" xlink:to="loc_nxdr_CashAndCashEquivalentsUnrealizedGain_7243327b-cf3a-4540-b88b-2aa0ef7e3408" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nxdr_CashAndCashEquivalentsUnrealizedLoss_a38226fd-8578-4754-91f4-c7889852c237" xlink:href="nxdr-20250930.xsd#nxdr_CashAndCashEquivalentsUnrealizedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashEquivalentsAtCarryingValueAbstract_82e173c2-5795-4da5-afa4-2f49b1474aaa" xlink:to="loc_nxdr_CashAndCashEquivalentsUnrealizedLoss_a38226fd-8578-4754-91f4-c7889852c237" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_4fcd4935-c2c2-4efb-bab1-827939d1df73" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashAndCashEquivalentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashEquivalentsAtCarryingValueAbstract_82e173c2-5795-4da5-afa4-2f49b1474aaa" xlink:to="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_4fcd4935-c2c2-4efb-bab1-827939d1df73" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableforsaleAmortizedCostAbstract_203858b4-59f7-4266-9b10-b8677ef2aae4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableforsaleAmortizedCostAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashAndCashEquivalentsLineItems_3dd7a930-06cc-4087-87c3-d079a4b2062f" xlink:to="loc_us-gaap_DebtSecuritiesAvailableforsaleAmortizedCostAbstract_203858b4-59f7-4266-9b10-b8677ef2aae4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_40e27f08-c3c5-4984-aadf-8aef1096c097" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtSecuritiesAvailableforsaleAmortizedCostAbstract_203858b4-59f7-4266-9b10-b8677ef2aae4" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_40e27f08-c3c5-4984-aadf-8aef1096c097" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_0f83be1c-4169-432b-85f7-b603b215cca8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtSecuritiesAvailableforsaleAmortizedCostAbstract_203858b4-59f7-4266-9b10-b8677ef2aae4" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_0f83be1c-4169-432b-85f7-b603b215cca8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_cf11cd63-cb57-4fb8-bad5-e854cc35b381" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtSecuritiesAvailableforsaleAmortizedCostAbstract_203858b4-59f7-4266-9b10-b8677ef2aae4" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_cf11cd63-cb57-4fb8-bad5-e854cc35b381" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecuritiesCurrent_ac7430c1-4747-4e98-8c52-bf10af86ec6f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecuritiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtSecuritiesAvailableforsaleAmortizedCostAbstract_203858b4-59f7-4266-9b10-b8677ef2aae4" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecuritiesCurrent_ac7430c1-4747-4e98-8c52-bf10af86ec6f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_nxdr_CashEquivalentsAtCarryingValueAndDebtSecuritiesAvailableForSaleAmortizedCostAbstract_0f8309d8-db10-41ec-bb5a-d3032b0bd9c6" xlink:href="nxdr-20250930.xsd#nxdr_CashEquivalentsAtCarryingValueAndDebtSecuritiesAvailableForSaleAmortizedCostAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashAndCashEquivalentsLineItems_3dd7a930-06cc-4087-87c3-d079a4b2062f" xlink:to="loc_nxdr_CashEquivalentsAtCarryingValueAndDebtSecuritiesAvailableForSaleAmortizedCostAbstract_0f8309d8-db10-41ec-bb5a-d3032b0bd9c6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nxdr_CashEquivalentsAtCarryingValueAndDebtSecuritiesAvailableForSaleAmortizedCost_c5b5ed66-17fa-4904-bfa5-a87914ebf7cd" xlink:href="nxdr-20250930.xsd#nxdr_CashEquivalentsAtCarryingValueAndDebtSecuritiesAvailableForSaleAmortizedCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nxdr_CashEquivalentsAtCarryingValueAndDebtSecuritiesAvailableForSaleAmortizedCostAbstract_0f8309d8-db10-41ec-bb5a-d3032b0bd9c6" xlink:to="loc_nxdr_CashEquivalentsAtCarryingValueAndDebtSecuritiesAvailableForSaleAmortizedCost_c5b5ed66-17fa-4904-bfa5-a87914ebf7cd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nxdr_CashEquivalentsAtCarryingValueAndDebtSecuritiesAvailableForSaleUnrealizedGain_dddafe96-a690-468f-beb9-d61f38f0ce88" xlink:href="nxdr-20250930.xsd#nxdr_CashEquivalentsAtCarryingValueAndDebtSecuritiesAvailableForSaleUnrealizedGain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nxdr_CashEquivalentsAtCarryingValueAndDebtSecuritiesAvailableForSaleAmortizedCostAbstract_0f8309d8-db10-41ec-bb5a-d3032b0bd9c6" xlink:to="loc_nxdr_CashEquivalentsAtCarryingValueAndDebtSecuritiesAvailableForSaleUnrealizedGain_dddafe96-a690-468f-beb9-d61f38f0ce88" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nxdr_CashEquivalentsAtCarryingValueAndDebtSecuritiesAvailableForSaleUnrealizedLoss_9fb9efdd-79c2-49a4-8cf2-bfc4c717324e" xlink:href="nxdr-20250930.xsd#nxdr_CashEquivalentsAtCarryingValueAndDebtSecuritiesAvailableForSaleUnrealizedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nxdr_CashEquivalentsAtCarryingValueAndDebtSecuritiesAvailableForSaleAmortizedCostAbstract_0f8309d8-db10-41ec-bb5a-d3032b0bd9c6" xlink:to="loc_nxdr_CashEquivalentsAtCarryingValueAndDebtSecuritiesAvailableForSaleUnrealizedLoss_9fb9efdd-79c2-49a4-8cf2-bfc4c717324e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_nxdr_CashEquivalentsFairValueDisclosureAndDebtSecuritiesAvailableForSaleCurrent_d9c6dbba-1fa1-48e0-b4cc-c59206e48f55" xlink:href="nxdr-20250930.xsd#nxdr_CashEquivalentsFairValueDisclosureAndDebtSecuritiesAvailableForSaleCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nxdr_CashEquivalentsAtCarryingValueAndDebtSecuritiesAvailableForSaleAmortizedCostAbstract_0f8309d8-db10-41ec-bb5a-d3032b0bd9c6" xlink:to="loc_nxdr_CashEquivalentsFairValueDisclosureAndDebtSecuritiesAvailableForSaleCurrent_d9c6dbba-1fa1-48e0-b4cc-c59206e48f55" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nextdoor.com/role/CashEquivalentsandMarketableSecuritiesScheduleofGrossUnrealizedLossesForAvailableForSaleofSecuritiesDetails" xlink:type="simple" xlink:href="nxdr-20250930.xsd#CashEquivalentsandMarketableSecuritiesScheduleofGrossUnrealizedLossesForAvailableForSaleofSecuritiesDetails"/>
  <link:definitionLink xlink:role="http://www.nextdoor.com/role/CashEquivalentsandMarketableSecuritiesScheduleofGrossUnrealizedLossesForAvailableForSaleofSecuritiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsLineItems_681f3cd9-3843-44d0-be44-49b441d07065" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashAndCashEquivalentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfCashAndCashEquivalentsTable_a583cdaa-6c06-448c-8187-f749f1b6d2e2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfCashAndCashEquivalentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_CashAndCashEquivalentsLineItems_681f3cd9-3843-44d0-be44-49b441d07065" xlink:to="loc_us-gaap_ScheduleOfCashAndCashEquivalentsTable_a583cdaa-6c06-448c-8187-f749f1b6d2e2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_1236b25f-b5db-433f-9b74-29fbe5303f92" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCashAndCashEquivalentsTable_a583cdaa-6c06-448c-8187-f749f1b6d2e2" xlink:to="loc_us-gaap_FinancialInstrumentAxis_1236b25f-b5db-433f-9b74-29fbe5303f92" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_1236b25f-b5db-433f-9b74-29fbe5303f92_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_1236b25f-b5db-433f-9b74-29fbe5303f92" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_1236b25f-b5db-433f-9b74-29fbe5303f92_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_758d604d-b800-42b1-bce5-2ff7302f69b5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_1236b25f-b5db-433f-9b74-29fbe5303f92" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_758d604d-b800-42b1-bce5-2ff7302f69b5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CertificatesOfDepositMember_b844a539-d64a-4100-8215-ef15d4790aa0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CertificatesOfDepositMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_758d604d-b800-42b1-bce5-2ff7302f69b5" xlink:to="loc_us-gaap_CertificatesOfDepositMember_b844a539-d64a-4100-8215-ef15d4790aa0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialPaperMember_70004b02-92e4-485e-8298-e85423509306" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommercialPaperMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_758d604d-b800-42b1-bce5-2ff7302f69b5" xlink:to="loc_us-gaap_CommercialPaperMember_70004b02-92e4-485e-8298-e85423509306" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateDebtSecuritiesMember_8371f2d0-046f-4fe2-92e9-c53d0ec6132d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CorporateDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_758d604d-b800-42b1-bce5-2ff7302f69b5" xlink:to="loc_us-gaap_CorporateDebtSecuritiesMember_8371f2d0-046f-4fe2-92e9-c53d0ec6132d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USTreasurySecuritiesMember_4d3f2bb9-c4b0-4855-b69f-84f5660588e6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_USTreasurySecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_758d604d-b800-42b1-bce5-2ff7302f69b5" xlink:to="loc_us-gaap_USTreasurySecuritiesMember_4d3f2bb9-c4b0-4855-b69f-84f5660588e6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetBackedSecuritiesMember_ef826bf5-62b6-44e9-ba57-15fce10d88a9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_758d604d-b800-42b1-bce5-2ff7302f69b5" xlink:to="loc_us-gaap_AssetBackedSecuritiesMember_ef826bf5-62b6-44e9-ba57-15fce10d88a9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months_0e968c32-caff-4b47-9a22-19a278759247" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashAndCashEquivalentsLineItems_681f3cd9-3843-44d0-be44-49b441d07065" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months_0e968c32-caff-4b47-9a22-19a278759247" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss_8b8e7b41-afa4-498f-b545-daed5f9b32df" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashAndCashEquivalentsLineItems_681f3cd9-3843-44d0-be44-49b441d07065" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss_8b8e7b41-afa4-498f-b545-daed5f9b32df" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger_0919c47d-56ed-4ab2-87ef-6942d2c92ba9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashAndCashEquivalentsLineItems_681f3cd9-3843-44d0-be44-49b441d07065" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger_0919c47d-56ed-4ab2-87ef-6942d2c92ba9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss_271af544-7c95-44bf-b69f-a9901fe9552b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashAndCashEquivalentsLineItems_681f3cd9-3843-44d0-be44-49b441d07065" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss_271af544-7c95-44bf-b69f-a9901fe9552b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition_09c5ecb9-115c-487a-a618-2c53a19a2778" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashAndCashEquivalentsLineItems_681f3cd9-3843-44d0-be44-49b441d07065" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition_09c5ecb9-115c-487a-a618-2c53a19a2778" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss_ca8f1fa1-e754-40f2-9860-ba551d7c3959" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashAndCashEquivalentsLineItems_681f3cd9-3843-44d0-be44-49b441d07065" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss_ca8f1fa1-e754-40f2-9860-ba551d7c3959" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nextdoor.com/role/FairValueMeasurementsNarrativeDetails" xlink:type="simple" xlink:href="nxdr-20250930.xsd#FairValueMeasurementsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.nextdoor.com/role/FairValueMeasurementsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_1a116cbe-ce77-48ac-a65e-efc4ac88f3ee" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_26f2eb64-d12c-4876-ac55-5dffa9676212" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_1a116cbe-ce77-48ac-a65e-efc4ac88f3ee" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_26f2eb64-d12c-4876-ac55-5dffa9676212" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_ee2100ca-4ce8-4b08-a263-3243c9906c11" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_26f2eb64-d12c-4876-ac55-5dffa9676212" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_ee2100ca-4ce8-4b08-a263-3243c9906c11" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_ee2100ca-4ce8-4b08-a263-3243c9906c11_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_ee2100ca-4ce8-4b08-a263-3243c9906c11" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_ee2100ca-4ce8-4b08-a263-3243c9906c11_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_9b5c1b0a-ee55-4701-82f1-6757cbba4918" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_ee2100ca-4ce8-4b08-a263-3243c9906c11" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_9b5c1b0a-ee55-4701-82f1-6757cbba4918" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_c21f9972-e894-4cce-8335-76318e1618f4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_9b5c1b0a-ee55-4701-82f1-6757cbba4918" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_c21f9972-e894-4cce-8335-76318e1618f4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_ac4c5ec2-a08c-4de9-a6b7-77c9e2b89d74" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_26f2eb64-d12c-4876-ac55-5dffa9676212" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_ac4c5ec2-a08c-4de9-a6b7-77c9e2b89d74" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_ac4c5ec2-a08c-4de9-a6b7-77c9e2b89d74_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_ac4c5ec2-a08c-4de9-a6b7-77c9e2b89d74" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_ac4c5ec2-a08c-4de9-a6b7-77c9e2b89d74_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_8a50ce20-af39-469b-b1d2-97dd484fa3d8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_ac4c5ec2-a08c-4de9-a6b7-77c9e2b89d74" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_8a50ce20-af39-469b-b1d2-97dd484fa3d8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_d054b5ed-ad09-46aa-8144-e665e340f009" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_8a50ce20-af39-469b-b1d2-97dd484fa3d8" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_d054b5ed-ad09-46aa-8144-e665e340f009" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_1e114359-f274-4e5e-b833-6a0fadd49288" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_26f2eb64-d12c-4876-ac55-5dffa9676212" xlink:to="loc_srt_CounterpartyNameAxis_1e114359-f274-4e5e-b833-6a0fadd49288" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_1e114359-f274-4e5e-b833-6a0fadd49288_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_1e114359-f274-4e5e-b833-6a0fadd49288" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_1e114359-f274-4e5e-b833-6a0fadd49288_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_8495f5f2-e641-4b1a-93a3-7adb6e0ae2f6" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_1e114359-f274-4e5e-b833-6a0fadd49288" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_8495f5f2-e641-4b1a-93a3-7adb6e0ae2f6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nxdr_OpportunityFinanceNetworkMember_da95df07-0c00-44aa-83f6-7772708df20d" xlink:href="nxdr-20250930.xsd#nxdr_OpportunityFinanceNetworkMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_8495f5f2-e641-4b1a-93a3-7adb6e0ae2f6" xlink:to="loc_nxdr_OpportunityFinanceNetworkMember_da95df07-0c00-44aa-83f6-7772708df20d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_be86a69a-8f0c-49be-8c61-2ab40a36c459" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_1a116cbe-ce77-48ac-a65e-efc4ac88f3ee" xlink:to="loc_us-gaap_AssetsFairValueDisclosure_be86a69a-8f0c-49be-8c61-2ab40a36c459" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialLiabilitiesFairValueDisclosure_d9ed6b59-7fbb-4cd5-883b-ca1e28735510" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialLiabilitiesFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_1a116cbe-ce77-48ac-a65e-efc4ac88f3ee" xlink:to="loc_us-gaap_FinancialLiabilitiesFairValueDisclosure_d9ed6b59-7fbb-4cd5-883b-ca1e28735510" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nxdr_LoansReceivableMaximumLendingCapacity_5b14e13e-cab0-4ff6-83f8-4ef0f4edae03" xlink:href="nxdr-20250930.xsd#nxdr_LoansReceivableMaximumLendingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_1a116cbe-ce77-48ac-a65e-efc4ac88f3ee" xlink:to="loc_nxdr_LoansReceivableMaximumLendingCapacity_5b14e13e-cab0-4ff6-83f8-4ef0f4edae03" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nxdr_LoansReceivableLendingTerm_d818c65a-529a-492b-9dd6-ffd55ee89dcf" xlink:href="nxdr-20250930.xsd#nxdr_LoansReceivableLendingTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_1a116cbe-ce77-48ac-a65e-efc4ac88f3ee" xlink:to="loc_nxdr_LoansReceivableLendingTerm_d818c65a-529a-492b-9dd6-ffd55ee89dcf" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nextdoor.com/role/FairValueMeasurementsFinancialAssetsDetails" xlink:type="simple" xlink:href="nxdr-20250930.xsd#FairValueMeasurementsFinancialAssetsDetails"/>
  <link:definitionLink xlink:role="http://www.nextdoor.com/role/FairValueMeasurementsFinancialAssetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_ec6574e5-7109-4fe0-a362-3d395fda50d1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_bde01fa8-9a9f-472d-b556-ab471798b563" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_ec6574e5-7109-4fe0-a362-3d395fda50d1" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_bde01fa8-9a9f-472d-b556-ab471798b563" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_f473d4fd-6902-4cdd-9c16-00c4a4614f78" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_bde01fa8-9a9f-472d-b556-ab471798b563" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_f473d4fd-6902-4cdd-9c16-00c4a4614f78" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_f473d4fd-6902-4cdd-9c16-00c4a4614f78_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_f473d4fd-6902-4cdd-9c16-00c4a4614f78" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_f473d4fd-6902-4cdd-9c16-00c4a4614f78_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_68cc7d05-9b9d-45c1-a7d8-0fda6175b38b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_f473d4fd-6902-4cdd-9c16-00c4a4614f78" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_68cc7d05-9b9d-45c1-a7d8-0fda6175b38b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_09bc092f-580d-4b96-9672-d4c827617c0d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_68cc7d05-9b9d-45c1-a7d8-0fda6175b38b" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_09bc092f-580d-4b96-9672-d4c827617c0d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_bf553343-3554-4b9b-93be-e8565011cf0a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_68cc7d05-9b9d-45c1-a7d8-0fda6175b38b" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_bf553343-3554-4b9b-93be-e8565011cf0a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_b174cb29-a107-4c7e-96af-55b5ced69cf9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_bde01fa8-9a9f-472d-b556-ab471798b563" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_b174cb29-a107-4c7e-96af-55b5ced69cf9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_b174cb29-a107-4c7e-96af-55b5ced69cf9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_b174cb29-a107-4c7e-96af-55b5ced69cf9" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_b174cb29-a107-4c7e-96af-55b5ced69cf9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_9c62375d-f9c1-4edb-adbf-c127f1febaf4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_b174cb29-a107-4c7e-96af-55b5ced69cf9" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_9c62375d-f9c1-4edb-adbf-c127f1febaf4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_eee1a388-8edb-43b2-8377-1041bc81fa9f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_9c62375d-f9c1-4edb-adbf-c127f1febaf4" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_eee1a388-8edb-43b2-8377-1041bc81fa9f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAxis_ee19b470-32ca-4eea-89b4-642807440f80" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashAndCashEquivalentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_bde01fa8-9a9f-472d-b556-ab471798b563" xlink:to="loc_us-gaap_CashAndCashEquivalentsAxis_ee19b470-32ca-4eea-89b4-642807440f80" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_ee19b470-32ca-4eea-89b4-642807440f80_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CashAndCashEquivalentsAxis_ee19b470-32ca-4eea-89b4-642807440f80" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_ee19b470-32ca-4eea-89b4-642807440f80_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_fdfeb294-ede0-4112-8cf1-2de15ca299c3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CashAndCashEquivalentsAxis_ee19b470-32ca-4eea-89b4-642807440f80" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_fdfeb294-ede0-4112-8cf1-2de15ca299c3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MoneyMarketFundsMember_4f19a06d-1419-4fff-8efc-807e8a0fdbed" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MoneyMarketFundsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_fdfeb294-ede0-4112-8cf1-2de15ca299c3" xlink:to="loc_us-gaap_MoneyMarketFundsMember_4f19a06d-1419-4fff-8efc-807e8a0fdbed" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateDebtSecuritiesMember_c9800277-5005-4cb3-be7c-7c41e2e38483" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CorporateDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_fdfeb294-ede0-4112-8cf1-2de15ca299c3" xlink:to="loc_us-gaap_CorporateDebtSecuritiesMember_c9800277-5005-4cb3-be7c-7c41e2e38483" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialPaperMember_fb761f3f-1a17-4c75-aa4a-98c84b05d628" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommercialPaperMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_fdfeb294-ede0-4112-8cf1-2de15ca299c3" xlink:to="loc_us-gaap_CommercialPaperMember_fb761f3f-1a17-4c75-aa4a-98c84b05d628" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_21b9fd60-7341-447b-b687-a3b735b79e73" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_bde01fa8-9a9f-472d-b556-ab471798b563" xlink:to="loc_us-gaap_FinancialInstrumentAxis_21b9fd60-7341-447b-b687-a3b735b79e73" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_21b9fd60-7341-447b-b687-a3b735b79e73_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_21b9fd60-7341-447b-b687-a3b735b79e73" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_21b9fd60-7341-447b-b687-a3b735b79e73_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_497a5798-6ed0-4e88-ab0b-740a7850955d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_21b9fd60-7341-447b-b687-a3b735b79e73" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_497a5798-6ed0-4e88-ab0b-740a7850955d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CertificatesOfDepositMember_1b25619e-9fa7-4bf4-9ba3-ecddcbca270a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CertificatesOfDepositMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_497a5798-6ed0-4e88-ab0b-740a7850955d" xlink:to="loc_us-gaap_CertificatesOfDepositMember_1b25619e-9fa7-4bf4-9ba3-ecddcbca270a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialPaperMember_da110ff8-8409-4213-8ea4-e4a7a8a0fb76" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommercialPaperMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_497a5798-6ed0-4e88-ab0b-740a7850955d" xlink:to="loc_us-gaap_CommercialPaperMember_da110ff8-8409-4213-8ea4-e4a7a8a0fb76" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateDebtSecuritiesMember_6d2966f8-6e2a-487b-b2ad-0371e575d153" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CorporateDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_497a5798-6ed0-4e88-ab0b-740a7850955d" xlink:to="loc_us-gaap_CorporateDebtSecuritiesMember_6d2966f8-6e2a-487b-b2ad-0371e575d153" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USTreasurySecuritiesMember_bc5b5ffc-372b-47aa-a8ae-44c7f365b6d3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_USTreasurySecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_497a5798-6ed0-4e88-ab0b-740a7850955d" xlink:to="loc_us-gaap_USTreasurySecuritiesMember_bc5b5ffc-372b-47aa-a8ae-44c7f365b6d3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetBackedSecuritiesMember_a1a962fd-982b-4fe2-8ee4-6fee767e21c6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_497a5798-6ed0-4e88-ab0b-740a7850955d" xlink:to="loc_us-gaap_AssetBackedSecuritiesMember_a1a962fd-982b-4fe2-8ee4-6fee767e21c6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_02477e60-ca45-4c43-8afc-3da7451a1611" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashAndCashEquivalentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_ec6574e5-7109-4fe0-a362-3d395fda50d1" xlink:to="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_02477e60-ca45-4c43-8afc-3da7451a1611" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_24b22b53-4449-45b8-ab43-1e1aa97ab978" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_ec6574e5-7109-4fe0-a362-3d395fda50d1" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_24b22b53-4449-45b8-ab43-1e1aa97ab978" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_d82c758f-1d37-4257-80ce-5612e4f5c7fe" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_ec6574e5-7109-4fe0-a362-3d395fda50d1" xlink:to="loc_us-gaap_AssetsFairValueDisclosure_d82c758f-1d37-4257-80ce-5612e4f5c7fe" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nextdoor.com/role/FairValueMeasurementsFinancialInstrumentsAssetsandLiabilitiesNotRecordedatFairValueDetails" xlink:type="simple" xlink:href="nxdr-20250930.xsd#FairValueMeasurementsFinancialInstrumentsAssetsandLiabilitiesNotRecordedatFairValueDetails"/>
  <link:definitionLink xlink:role="http://www.nextdoor.com/role/FairValueMeasurementsFinancialInstrumentsAssetsandLiabilitiesNotRecordedatFairValueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_c3e7286b-5ab2-4d51-969c-f634bbd25311" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_9f553c8b-d1da-4467-9aac-70900681404e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_c3e7286b-5ab2-4d51-969c-f634bbd25311" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_9f553c8b-d1da-4467-9aac-70900681404e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementBasisAxis_d72c134d-6014-4d0e-8f92-0afb5ec1df75" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByMeasurementBasisAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_9f553c8b-d1da-4467-9aac-70900681404e" xlink:to="loc_us-gaap_FairValueByMeasurementBasisAxis_d72c134d-6014-4d0e-8f92-0afb5ec1df75" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_d72c134d-6014-4d0e-8f92-0afb5ec1df75_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_d72c134d-6014-4d0e-8f92-0afb5ec1df75" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_d72c134d-6014-4d0e-8f92-0afb5ec1df75_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueDisclosureItemAmountsDomain_53568c2a-8aad-4c08-95b0-b078f3e68435" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueDisclosureItemAmountsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_d72c134d-6014-4d0e-8f92-0afb5ec1df75" xlink:to="loc_us-gaap_FairValueDisclosureItemAmountsDomain_53568c2a-8aad-4c08-95b0-b078f3e68435" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_cf67a615-e0a8-48d4-9567-fb76b9739cc7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_53568c2a-8aad-4c08-95b0-b078f3e68435" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_cf67a615-e0a8-48d4-9567-fb76b9739cc7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_9492456c-5b1c-4077-a4ab-e51ffb9dbfdd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CarryingReportedAmountFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_cf67a615-e0a8-48d4-9567-fb76b9739cc7" xlink:to="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_9492456c-5b1c-4077-a4ab-e51ffb9dbfdd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_88f0b105-581d-437b-8493-29ad41771e18" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EstimateOfFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_cf67a615-e0a8-48d4-9567-fb76b9739cc7" xlink:to="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_88f0b105-581d-437b-8493-29ad41771e18" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_1f4f6f9d-6a0c-4bc8-a689-6712677f22c3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_9f553c8b-d1da-4467-9aac-70900681404e" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_1f4f6f9d-6a0c-4bc8-a689-6712677f22c3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_1f4f6f9d-6a0c-4bc8-a689-6712677f22c3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_1f4f6f9d-6a0c-4bc8-a689-6712677f22c3" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_1f4f6f9d-6a0c-4bc8-a689-6712677f22c3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_32d891ba-aaaf-4278-b9af-e6d1208cdf99" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_1f4f6f9d-6a0c-4bc8-a689-6712677f22c3" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_32d891ba-aaaf-4278-b9af-e6d1208cdf99" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_1b1a5170-dabc-4d6b-b971-06411889c94b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_32d891ba-aaaf-4278-b9af-e6d1208cdf99" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_1b1a5170-dabc-4d6b-b971-06411889c94b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_a3243744-9306-4f3e-ba7b-1398f10458a0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_32d891ba-aaaf-4278-b9af-e6d1208cdf99" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_a3243744-9306-4f3e-ba7b-1398f10458a0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_d6f34d7c-8e09-41ca-88de-00d4c3ce0cd8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_32d891ba-aaaf-4278-b9af-e6d1208cdf99" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_d6f34d7c-8e09-41ca-88de-00d4c3ce0cd8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NotesReceivableFairValueDisclosure_7012697d-c341-4f38-a540-a38b20ed49a5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NotesReceivableFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_c3e7286b-5ab2-4d51-969c-f634bbd25311" xlink:to="loc_us-gaap_NotesReceivableFairValueDisclosure_7012697d-c341-4f38-a540-a38b20ed49a5" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nextdoor.com/role/CommitmentsandContingenciesDetails" xlink:type="simple" xlink:href="nxdr-20250930.xsd#CommitmentsandContingenciesDetails"/>
  <link:definitionLink xlink:role="http://www.nextdoor.com/role/CommitmentsandContingenciesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsLineItems_390d2d34-9de7-439c-83a1-845abdba2cae" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherCommitmentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsTable_3af22ffa-a0fb-45e0-81af-5cf0e1ae754f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherCommitmentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_390d2d34-9de7-439c-83a1-845abdba2cae" xlink:to="loc_us-gaap_OtherCommitmentsTable_3af22ffa-a0fb-45e0-81af-5cf0e1ae754f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusAxis_e890bc90-bd7f-42e0-904c-26a994c2199f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LitigationStatusAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OtherCommitmentsTable_3af22ffa-a0fb-45e0-81af-5cf0e1ae754f" xlink:to="loc_us-gaap_LitigationStatusAxis_e890bc90-bd7f-42e0-904c-26a994c2199f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_e890bc90-bd7f-42e0-904c-26a994c2199f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LitigationStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LitigationStatusAxis_e890bc90-bd7f-42e0-904c-26a994c2199f" xlink:to="loc_us-gaap_LitigationStatusDomain_e890bc90-bd7f-42e0-904c-26a994c2199f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_1e36d1b7-5c90-4cee-92d5-3932babfb73d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LitigationStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LitigationStatusAxis_e890bc90-bd7f-42e0-904c-26a994c2199f" xlink:to="loc_us-gaap_LitigationStatusDomain_1e36d1b7-5c90-4cee-92d5-3932babfb73d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PendingLitigationMember_c6431273-71d2-4a27-bd00-46899413a08a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PendingLitigationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LitigationStatusDomain_1e36d1b7-5c90-4cee-92d5-3932babfb73d" xlink:to="loc_us-gaap_PendingLitigationMember_c6431273-71d2-4a27-bd00-46899413a08a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseAxis_106479ce-2624-430e-b6de-8740bb8cc7cd" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_LitigationCaseAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OtherCommitmentsTable_3af22ffa-a0fb-45e0-81af-5cf0e1ae754f" xlink:to="loc_srt_LitigationCaseAxis_106479ce-2624-430e-b6de-8740bb8cc7cd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_106479ce-2624-430e-b6de-8740bb8cc7cd_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_LitigationCaseAxis_106479ce-2624-430e-b6de-8740bb8cc7cd" xlink:to="loc_srt_LitigationCaseTypeDomain_106479ce-2624-430e-b6de-8740bb8cc7cd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_1ff43c44-81d5-435f-aab9-7c5f9dfd42da" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_LitigationCaseAxis_106479ce-2624-430e-b6de-8740bb8cc7cd" xlink:to="loc_srt_LitigationCaseTypeDomain_1ff43c44-81d5-435f-aab9-7c5f9dfd42da" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nxdr_ClassActionLitigationMember_385c3b16-1595-4fbf-9774-3fb910f6c1ea" xlink:href="nxdr-20250930.xsd#nxdr_ClassActionLitigationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_1ff43c44-81d5-435f-aab9-7c5f9dfd42da" xlink:to="loc_nxdr_ClassActionLitigationMember_385c3b16-1595-4fbf-9774-3fb910f6c1ea" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNewClaimsFiledNumber_7fa49ee2-46f5-47b1-9824-f489235b6ec8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyNewClaimsFiledNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_390d2d34-9de7-439c-83a1-845abdba2cae" xlink:to="loc_us-gaap_LossContingencyNewClaimsFiledNumber_7fa49ee2-46f5-47b1-9824-f489235b6ec8" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nextdoor.com/role/CommonStockandStockholdersEquityNarrativeDetails" xlink:type="simple" xlink:href="nxdr-20250930.xsd#CommonStockandStockholdersEquityNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.nextdoor.com/role/CommonStockandStockholdersEquityNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_ce6a262b-7f1c-48b1-be36-efaf32105877" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_e0bfc92e-e85e-4b66-8e69-8503920aeda2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_ce6a262b-7f1c-48b1-be36-efaf32105877" xlink:to="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_e0bfc92e-e85e-4b66-8e69-8503920aeda2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_63d7402d-74b8-48f8-911b-0356cce7a1bf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_e0bfc92e-e85e-4b66-8e69-8503920aeda2" xlink:to="loc_us-gaap_PlanNameAxis_63d7402d-74b8-48f8-911b-0356cce7a1bf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_63d7402d-74b8-48f8-911b-0356cce7a1bf_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_63d7402d-74b8-48f8-911b-0356cce7a1bf" xlink:to="loc_us-gaap_PlanNameDomain_63d7402d-74b8-48f8-911b-0356cce7a1bf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_a45db6be-989e-4489-920e-0b89c9e34288" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_63d7402d-74b8-48f8-911b-0356cce7a1bf" xlink:to="loc_us-gaap_PlanNameDomain_a45db6be-989e-4489-920e-0b89c9e34288" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nxdr_The2021PlanMember_905c886c-d5ec-4006-b1c1-2f10c65a460b" xlink:href="nxdr-20250930.xsd#nxdr_The2021PlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_a45db6be-989e-4489-920e-0b89c9e34288" xlink:to="loc_nxdr_The2021PlanMember_905c886c-d5ec-4006-b1c1-2f10c65a460b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_13dc2ed4-1dca-48c8-b806-6cff534f3d3c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_e0bfc92e-e85e-4b66-8e69-8503920aeda2" xlink:to="loc_us-gaap_AwardTypeAxis_13dc2ed4-1dca-48c8-b806-6cff534f3d3c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_13dc2ed4-1dca-48c8-b806-6cff534f3d3c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_13dc2ed4-1dca-48c8-b806-6cff534f3d3c" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_13dc2ed4-1dca-48c8-b806-6cff534f3d3c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_e02d8332-9872-4f61-b9e3-bafcbcc6f365" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_13dc2ed4-1dca-48c8-b806-6cff534f3d3c" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_e02d8332-9872-4f61-b9e3-bafcbcc6f365" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockMember_aeac06c5-215f-4cb4-add3-3fd294c00f8f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_e02d8332-9872-4f61-b9e3-bafcbcc6f365" xlink:to="loc_us-gaap_EmployeeStockMember_aeac06c5-215f-4cb4-add3-3fd294c00f8f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_4e394fea-8d70-445f-abde-2a9066cd7b9d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_e02d8332-9872-4f61-b9e3-bafcbcc6f365" xlink:to="loc_us-gaap_EmployeeStockOptionMember_4e394fea-8d70-445f-abde-2a9066cd7b9d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nxdr_ShareBasedPaymentArrangementOptionGranteesOwningMoreThanTenPercentOfVotingPowerMember_fe557d3e-4818-4c43-b685-35af7a8f0560" xlink:href="nxdr-20250930.xsd#nxdr_ShareBasedPaymentArrangementOptionGranteesOwningMoreThanTenPercentOfVotingPowerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_e02d8332-9872-4f61-b9e3-bafcbcc6f365" xlink:to="loc_nxdr_ShareBasedPaymentArrangementOptionGranteesOwningMoreThanTenPercentOfVotingPowerMember_fe557d3e-4818-4c43-b685-35af7a8f0560" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_4c1d4ef7-b1d7-4626-bd01-2362504d5959" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_e02d8332-9872-4f61-b9e3-bafcbcc6f365" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_4c1d4ef7-b1d7-4626-bd01-2362504d5959" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_nxdr_MarketBasedPerformanceStockUnitMember_16bd0ad1-aabc-4877-8f1c-84c515c83292" xlink:href="nxdr-20250930.xsd#nxdr_MarketBasedPerformanceStockUnitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_e02d8332-9872-4f61-b9e3-bafcbcc6f365" xlink:to="loc_nxdr_MarketBasedPerformanceStockUnitMember_16bd0ad1-aabc-4877-8f1c-84c515c83292" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_d6eae5f5-a6fc-4fbc-b9d7-e61c3ada2849" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_e0bfc92e-e85e-4b66-8e69-8503920aeda2" xlink:to="loc_us-gaap_StatementClassOfStockAxis_d6eae5f5-a6fc-4fbc-b9d7-e61c3ada2849" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_d6eae5f5-a6fc-4fbc-b9d7-e61c3ada2849_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_d6eae5f5-a6fc-4fbc-b9d7-e61c3ada2849" xlink:to="loc_us-gaap_ClassOfStockDomain_d6eae5f5-a6fc-4fbc-b9d7-e61c3ada2849_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_0e3991eb-0b27-4564-add9-95146809fa33" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_d6eae5f5-a6fc-4fbc-b9d7-e61c3ada2849" xlink:to="loc_us-gaap_ClassOfStockDomain_0e3991eb-0b27-4564-add9-95146809fa33" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_9ed9a728-e7b7-4079-97a1-cf3379d5e9d1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_0e3991eb-0b27-4564-add9-95146809fa33" xlink:to="loc_us-gaap_CommonClassAMember_9ed9a728-e7b7-4079-97a1-cf3379d5e9d1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassBMember_564cb871-a7d6-4c6e-923d-a64916ff7345" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonClassBMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_0e3991eb-0b27-4564-add9-95146809fa33" xlink:to="loc_us-gaap_CommonClassBMember_564cb871-a7d6-4c6e-923d-a64916ff7345" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_e511bd7d-73aa-4bb7-97d8-23714fca6ed5" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_e0bfc92e-e85e-4b66-8e69-8503920aeda2" xlink:to="loc_srt_RangeAxis_e511bd7d-73aa-4bb7-97d8-23714fca6ed5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_e511bd7d-73aa-4bb7-97d8-23714fca6ed5_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_e511bd7d-73aa-4bb7-97d8-23714fca6ed5" xlink:to="loc_srt_RangeMember_e511bd7d-73aa-4bb7-97d8-23714fca6ed5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_9d7c01ec-b9e6-42be-a871-404482928cdf" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_e511bd7d-73aa-4bb7-97d8-23714fca6ed5" xlink:to="loc_srt_RangeMember_9d7c01ec-b9e6-42be-a871-404482928cdf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_e2354918-b184-407e-8a8a-ccccefc2bb1b" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_9d7c01ec-b9e6-42be-a871-404482928cdf" xlink:to="loc_srt_MinimumMember_e2354918-b184-407e-8a8a-ccccefc2bb1b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_5aa704d5-22e6-4918-a957-b049e41d5bd6" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_9d7c01ec-b9e6-42be-a871-404482928cdf" xlink:to="loc_srt_MaximumMember_5aa704d5-22e6-4918-a957-b049e41d5bd6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualAxis_f7b6d339-2aa9-4e4e-a47b-da8dee2ee1f0" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_TitleOfIndividualAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_e0bfc92e-e85e-4b66-8e69-8503920aeda2" xlink:to="loc_srt_TitleOfIndividualAxis_f7b6d339-2aa9-4e4e-a47b-da8dee2ee1f0" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_f7b6d339-2aa9-4e4e-a47b-da8dee2ee1f0_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_TitleOfIndividualAxis_f7b6d339-2aa9-4e4e-a47b-da8dee2ee1f0" xlink:to="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_f7b6d339-2aa9-4e4e-a47b-da8dee2ee1f0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_478a2bad-abfb-440b-bcb9-39e6393bdfcb" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_TitleOfIndividualAxis_f7b6d339-2aa9-4e4e-a47b-da8dee2ee1f0" xlink:to="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_478a2bad-abfb-440b-bcb9-39e6393bdfcb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ChiefExecutiveOfficerMember_db1d0dc0-9f0b-4d1a-9480-1ed81bf2c634" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ChiefExecutiveOfficerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_478a2bad-abfb-440b-bcb9-39e6393bdfcb" xlink:to="loc_srt_ChiefExecutiveOfficerMember_db1d0dc0-9f0b-4d1a-9480-1ed81bf2c634" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_341e28cb-0ada-4b7e-b7c4-53d7da791877" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockCapitalSharesReservedForFutureIssuance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_ce6a262b-7f1c-48b1-be36-efaf32105877" xlink:to="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_341e28cb-0ada-4b7e-b7c4-53d7da791877" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nxdr_ShareBasedCompensationArrangementByShareBasedPaymentAwardIncreaseInNumberOfSharesAvailableForGrantPercentageOfSharesOutstanding_015bc658-6865-417a-ade4-eb7316f6479a" xlink:href="nxdr-20250930.xsd#nxdr_ShareBasedCompensationArrangementByShareBasedPaymentAwardIncreaseInNumberOfSharesAvailableForGrantPercentageOfSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_ce6a262b-7f1c-48b1-be36-efaf32105877" xlink:to="loc_nxdr_ShareBasedCompensationArrangementByShareBasedPaymentAwardIncreaseInNumberOfSharesAvailableForGrantPercentageOfSharesOutstanding_015bc658-6865-417a-ade4-eb7316f6479a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent_2f4ba851-9742-4254-a456-acae0e9da089" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_ce6a262b-7f1c-48b1-be36-efaf32105877" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent_2f4ba851-9742-4254-a456-acae0e9da089" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockSharesAcquired_e1fdf4dc-8018-4c7c-9d0d-37a596c33c69" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TreasuryStockSharesAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_ce6a262b-7f1c-48b1-be36-efaf32105877" xlink:to="loc_us-gaap_TreasuryStockSharesAcquired_e1fdf4dc-8018-4c7c-9d0d-37a596c33c69" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StockRepurchaseProgramAuthorizedAmount1_5d763680-381b-415b-83a7-182fa19dc414" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StockRepurchaseProgramAuthorizedAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_ce6a262b-7f1c-48b1-be36-efaf32105877" xlink:to="loc_srt_StockRepurchaseProgramAuthorizedAmount1_5d763680-381b-415b-83a7-182fa19dc414" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_nxdr_StockRepurchaseProgramIncreaseAmount_e4980df6-aba4-48f0-bdd7-479b58b96b43" xlink:href="nxdr-20250930.xsd#nxdr_StockRepurchaseProgramIncreaseAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_ce6a262b-7f1c-48b1-be36-efaf32105877" xlink:to="loc_nxdr_StockRepurchaseProgramIncreaseAmount_e4980df6-aba4-48f0-bdd7-479b58b96b43" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockSharesRetired_2b1cb8ad-96cf-40be-8f05-f845e07fa6c4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TreasuryStockSharesRetired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_ce6a262b-7f1c-48b1-be36-efaf32105877" xlink:to="loc_us-gaap_TreasuryStockSharesRetired_2b1cb8ad-96cf-40be-8f05-f845e07fa6c4" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockAcquiredAverageCostPerShare_c27df2d5-996a-405d-8005-0df1f78198b5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TreasuryStockAcquiredAverageCostPerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_ce6a262b-7f1c-48b1-be36-efaf32105877" xlink:to="loc_us-gaap_TreasuryStockAcquiredAverageCostPerShare_c27df2d5-996a-405d-8005-0df1f78198b5" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockRetiredCostMethodAmount_4495cc6a-3a66-4619-a8a6-13299e652c58" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TreasuryStockRetiredCostMethodAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_ce6a262b-7f1c-48b1-be36-efaf32105877" xlink:to="loc_us-gaap_TreasuryStockRetiredCostMethodAmount_4495cc6a-3a66-4619-a8a6-13299e652c58" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_9eacf85e-e0d3-43e3-97ea-283881551ab5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_ce6a262b-7f1c-48b1-be36-efaf32105877" xlink:to="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_9eacf85e-e0d3-43e3-97ea-283881551ab5" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_nxdr_ShareBasedCompensationArrangementByShareBasedPaymentAwardThresholdMinimumProportionOfVotingPower_2d7c99e4-36af-4c8e-b4e3-323dcac1865d" xlink:href="nxdr-20250930.xsd#nxdr_ShareBasedCompensationArrangementByShareBasedPaymentAwardThresholdMinimumProportionOfVotingPower"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_ce6a262b-7f1c-48b1-be36-efaf32105877" xlink:to="loc_nxdr_ShareBasedCompensationArrangementByShareBasedPaymentAwardThresholdMinimumProportionOfVotingPower_2d7c99e4-36af-4c8e-b4e3-323dcac1865d" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_nxdr_ShareBasedCompensationArrangementByShareBasedPaymentAwardMinimumProportionOfFairMarketValueOfStockOptionsGrantedToGranteesThatOwnMoreThanTenPercentOfVotingPowerPercent_15a422e4-8969-4c12-818b-f64dffa7369e" xlink:href="nxdr-20250930.xsd#nxdr_ShareBasedCompensationArrangementByShareBasedPaymentAwardMinimumProportionOfFairMarketValueOfStockOptionsGrantedToGranteesThatOwnMoreThanTenPercentOfVotingPowerPercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_ce6a262b-7f1c-48b1-be36-efaf32105877" xlink:to="loc_nxdr_ShareBasedCompensationArrangementByShareBasedPaymentAwardMinimumProportionOfFairMarketValueOfStockOptionsGrantedToGranteesThatOwnMoreThanTenPercentOfVotingPowerPercent_15a422e4-8969-4c12-818b-f64dffa7369e" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_3acc8b9e-a997-4d3e-8416-3e5761c45bfe" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_ce6a262b-7f1c-48b1-be36-efaf32105877" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_3acc8b9e-a997-4d3e-8416-3e5761c45bfe" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_d94b0831-e025-4711-a312-9299283426bb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_ce6a262b-7f1c-48b1-be36-efaf32105877" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_d94b0831-e025-4711-a312-9299283426bb" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_2d9a6cc2-6dbc-47d3-82c9-cc091248abc2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_ce6a262b-7f1c-48b1-be36-efaf32105877" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_2d9a6cc2-6dbc-47d3-82c9-cc091248abc2" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_42d0c81e-9f7c-4d1f-8e5f-425b11d6d30e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_ce6a262b-7f1c-48b1-be36-efaf32105877" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_42d0c81e-9f7c-4d1f-8e5f-425b11d6d30e" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_e66c3268-c259-4817-b5c0-7ba783236f08" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_ce6a262b-7f1c-48b1-be36-efaf32105877" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_e66c3268-c259-4817-b5c0-7ba783236f08" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_9f2502ee-ec34-40e1-aba7-5ae47dc15db4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_ce6a262b-7f1c-48b1-be36-efaf32105877" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_9f2502ee-ec34-40e1-aba7-5ae47dc15db4" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_a4c8396a-e415-4d16-9fec-9968a9301c56" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_ce6a262b-7f1c-48b1-be36-efaf32105877" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_a4c8396a-e415-4d16-9fec-9968a9301c56" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensation_f88bbbc5-0bf5-4718-8990-140ceaa949bb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_ce6a262b-7f1c-48b1-be36-efaf32105877" xlink:to="loc_us-gaap_ShareBasedCompensation_f88bbbc5-0bf5-4718-8990-140ceaa949bb" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_d6067059-fa56-446b-b830-ab5a85fab1bb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_ce6a262b-7f1c-48b1-be36-efaf32105877" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_d6067059-fa56-446b-b830-ab5a85fab1bb" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_b0c4dcb0-9503-47f4-85a1-2ad19bfaab90" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_ce6a262b-7f1c-48b1-be36-efaf32105877" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_b0c4dcb0-9503-47f4-85a1-2ad19bfaab90" xlink:type="arc" order="21"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nextdoor.com/role/CommonStockandStockholdersEquityRestrictedStockUnitsDetails" xlink:type="simple" xlink:href="nxdr-20250930.xsd#CommonStockandStockholdersEquityRestrictedStockUnitsDetails"/>
  <link:definitionLink xlink:role="http://www.nextdoor.com/role/CommonStockandStockholdersEquityRestrictedStockUnitsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_578b419f-cf8c-40ae-aeea-ef61acfcc8c3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_2ee8ec4b-dceb-4ba8-b6cd-60d9bc91d444" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_578b419f-cf8c-40ae-aeea-ef61acfcc8c3" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_2ee8ec4b-dceb-4ba8-b6cd-60d9bc91d444" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_94ba09f7-b569-41a7-a400-3b502e9bf18e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_2ee8ec4b-dceb-4ba8-b6cd-60d9bc91d444" xlink:to="loc_us-gaap_AwardTypeAxis_94ba09f7-b569-41a7-a400-3b502e9bf18e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_94ba09f7-b569-41a7-a400-3b502e9bf18e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_94ba09f7-b569-41a7-a400-3b502e9bf18e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_94ba09f7-b569-41a7-a400-3b502e9bf18e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_ec2cfa6e-21bf-497d-acca-6b0162fad2b8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_94ba09f7-b569-41a7-a400-3b502e9bf18e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_ec2cfa6e-21bf-497d-acca-6b0162fad2b8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_e39d66f1-f45a-4c44-b19f-448314851ac8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_ec2cfa6e-21bf-497d-acca-6b0162fad2b8" xlink:to="loc_us-gaap_EmployeeStockOptionMember_e39d66f1-f45a-4c44-b19f-448314851ac8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_9acba96a-fef1-443d-b0fe-5548ec81b9f7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_578b419f-cf8c-40ae-aeea-ef61acfcc8c3" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_9acba96a-fef1-443d-b0fe-5548ec81b9f7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_c1123374-e46d-4455-9706-1987b715d419" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_9acba96a-fef1-443d-b0fe-5548ec81b9f7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_c1123374-e46d-4455-9706-1987b715d419" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_dd966714-da42-4102-ac90-89d0c2f72362" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_9acba96a-fef1-443d-b0fe-5548ec81b9f7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_dd966714-da42-4102-ac90-89d0c2f72362" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_f4bce2ac-f6fd-4f60-8035-dfb96ad4f80e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_9acba96a-fef1-443d-b0fe-5548ec81b9f7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_f4bce2ac-f6fd-4f60-8035-dfb96ad4f80e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_a54810e0-060b-4d64-900e-995fda35f59e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_9acba96a-fef1-443d-b0fe-5548ec81b9f7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_a54810e0-060b-4d64-900e-995fda35f59e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_886d271e-5efd-4f7b-ac66-566f78752c4b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_3a48153d-2edb-44b9-98e0-825ef984dcd0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_578b419f-cf8c-40ae-aeea-ef61acfcc8c3" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_3a48153d-2edb-44b9-98e0-825ef984dcd0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_e8c83bd8-0db0-4911-94a3-5a4476627214" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_3a48153d-2edb-44b9-98e0-825ef984dcd0" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_e8c83bd8-0db0-4911-94a3-5a4476627214" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_346db2dc-b684-43bd-b0d7-ad98cf2c59f0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_3a48153d-2edb-44b9-98e0-825ef984dcd0" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_346db2dc-b684-43bd-b0d7-ad98cf2c59f0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_86adae26-09ee-417b-8ac8-2d8c636e4358" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_3a48153d-2edb-44b9-98e0-825ef984dcd0" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_86adae26-09ee-417b-8ac8-2d8c636e4358" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_71e81ec1-70d1-4bfa-94b7-c3ca3c1dff7e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_3a48153d-2edb-44b9-98e0-825ef984dcd0" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_71e81ec1-70d1-4bfa-94b7-c3ca3c1dff7e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_3ed5892d-9d10-4aa7-82a4-d81fee8f5858" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nextdoor.com/role/CommonStockandStockholdersEquityFairValueAssumptionsDetails" xlink:type="simple" xlink:href="nxdr-20250930.xsd#CommonStockandStockholdersEquityFairValueAssumptionsDetails"/>
  <link:definitionLink xlink:role="http://www.nextdoor.com/role/CommonStockandStockholdersEquityFairValueAssumptionsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ee277087-bc19-4204-811c-3cc5c516e63d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_cbc96bc8-f3b7-4be6-bd6f-899afe7bfebc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ee277087-bc19-4204-811c-3cc5c516e63d" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_cbc96bc8-f3b7-4be6-bd6f-899afe7bfebc" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_4e448b1b-a812-4c32-8761-dea7cdf6d534" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_cbc96bc8-f3b7-4be6-bd6f-899afe7bfebc" xlink:to="loc_us-gaap_AwardTypeAxis_4e448b1b-a812-4c32-8761-dea7cdf6d534" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_4e448b1b-a812-4c32-8761-dea7cdf6d534_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_4e448b1b-a812-4c32-8761-dea7cdf6d534" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_4e448b1b-a812-4c32-8761-dea7cdf6d534_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_21128b2c-f0c0-4371-bced-0cb67ee70b0e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_4e448b1b-a812-4c32-8761-dea7cdf6d534" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_21128b2c-f0c0-4371-bced-0cb67ee70b0e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nxdr_MarketBasedPSUsMember_ea9f8df1-1ab3-4c1c-acee-b40d1f039416" xlink:href="nxdr-20250930.xsd#nxdr_MarketBasedPSUsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_21128b2c-f0c0-4371-bced-0cb67ee70b0e" xlink:to="loc_nxdr_MarketBasedPSUsMember_ea9f8df1-1ab3-4c1c-acee-b40d1f039416" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_073e82a5-f954-4d39-b08a-8c1d673e4b9e" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_cbc96bc8-f3b7-4be6-bd6f-899afe7bfebc" xlink:to="loc_srt_RangeAxis_073e82a5-f954-4d39-b08a-8c1d673e4b9e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_073e82a5-f954-4d39-b08a-8c1d673e4b9e_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_073e82a5-f954-4d39-b08a-8c1d673e4b9e" xlink:to="loc_srt_RangeMember_073e82a5-f954-4d39-b08a-8c1d673e4b9e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_fe254417-813c-4a18-ad1a-93b985922d5f" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_073e82a5-f954-4d39-b08a-8c1d673e4b9e" xlink:to="loc_srt_RangeMember_fe254417-813c-4a18-ad1a-93b985922d5f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_5c412912-daba-49f4-ac30-b783694fbc97" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_fe254417-813c-4a18-ad1a-93b985922d5f" xlink:to="loc_srt_MinimumMember_5c412912-daba-49f4-ac30-b783694fbc97" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_f13678ba-17cc-4c06-8624-80f863879461" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_fe254417-813c-4a18-ad1a-93b985922d5f" xlink:to="loc_srt_MaximumMember_f13678ba-17cc-4c06-8624-80f863879461" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum_7202aa8b-e192-453c-94d7-eca4210ee117" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ee277087-bc19-4204-811c-3cc5c516e63d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum_7202aa8b-e192-453c-94d7-eca4210ee117" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum_0411228a-2fe8-428d-bc38-7395b984f43d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ee277087-bc19-4204-811c-3cc5c516e63d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum_0411228a-2fe8-428d-bc38-7395b984f43d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_e299907c-81c1-4c7b-ad03-633e1d975ac5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ee277087-bc19-4204-811c-3cc5c516e63d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_e299907c-81c1-4c7b-ad03-633e1d975ac5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_a13042e6-d387-4f29-b749-86963ebbfdb7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ee277087-bc19-4204-811c-3cc5c516e63d" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_a13042e6-d387-4f29-b749-86963ebbfdb7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum_aa31e352-3a6f-4427-861a-b0bc7e753890" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ee277087-bc19-4204-811c-3cc5c516e63d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum_aa31e352-3a6f-4427-861a-b0bc7e753890" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum_897e47ee-dafb-4121-9c07-4cb79d227619" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ee277087-bc19-4204-811c-3cc5c516e63d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum_897e47ee-dafb-4121-9c07-4cb79d227619" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_5bd69779-2769-4180-b77f-0d280e452ea5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ee277087-bc19-4204-811c-3cc5c516e63d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_5bd69779-2769-4180-b77f-0d280e452ea5" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_d754ee31-3241-4e63-a093-c4b465b13080" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ee277087-bc19-4204-811c-3cc5c516e63d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_d754ee31-3241-4e63-a093-c4b465b13080" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nextdoor.com/role/CommonStockandStockholdersEquityStockbasedCompensationExpenseDetails" xlink:type="simple" xlink:href="nxdr-20250930.xsd#CommonStockandStockholdersEquityStockbasedCompensationExpenseDetails"/>
  <link:definitionLink xlink:role="http://www.nextdoor.com/role/CommonStockandStockholdersEquityStockbasedCompensationExpenseDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_6d22323f-5785-4ab3-baf0-1472b89e2b8b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_191f216e-3ebf-4e6c-bcaa-70a23a649c8d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_6d22323f-5785-4ab3-baf0-1472b89e2b8b" xlink:to="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_191f216e-3ebf-4e6c-bcaa-70a23a649c8d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_4202b4ca-2a54-4fb9-a90d-5d898ed8a15f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_191f216e-3ebf-4e6c-bcaa-70a23a649c8d" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_4202b4ca-2a54-4fb9-a90d-5d898ed8a15f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_4202b4ca-2a54-4fb9-a90d-5d898ed8a15f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_4202b4ca-2a54-4fb9-a90d-5d898ed8a15f" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_4202b4ca-2a54-4fb9-a90d-5d898ed8a15f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_75ad6d11-a230-4480-89d3-198347c37304" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_4202b4ca-2a54-4fb9-a90d-5d898ed8a15f" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_75ad6d11-a230-4480-89d3-198347c37304" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfSalesMember_439a79a5-8d56-4d7f-b011-9edba18deebd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CostOfSalesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_75ad6d11-a230-4480-89d3-198347c37304" xlink:to="loc_us-gaap_CostOfSalesMember_439a79a5-8d56-4d7f-b011-9edba18deebd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpenseMember_1bfea810-6d74-4bb8-b833-7f29b0532cfb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ResearchAndDevelopmentExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_75ad6d11-a230-4480-89d3-198347c37304" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpenseMember_1bfea810-6d74-4bb8-b833-7f29b0532cfb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingAndMarketingExpenseMember_9f4a7710-9295-4fea-b0d3-6ce49a9eea3e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SellingAndMarketingExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_75ad6d11-a230-4480-89d3-198347c37304" xlink:to="loc_us-gaap_SellingAndMarketingExpenseMember_9f4a7710-9295-4fea-b0d3-6ce49a9eea3e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpenseMember_ea4d2bd2-004d-4909-8230-58f153f8a021" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GeneralAndAdministrativeExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_75ad6d11-a230-4480-89d3-198347c37304" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpenseMember_ea4d2bd2-004d-4909-8230-58f153f8a021" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_8fd94e8e-f2d4-4b86-957f-791192d52b6a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_6d22323f-5785-4ab3-baf0-1472b89e2b8b" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_8fd94e8e-f2d4-4b86-957f-791192d52b6a" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nextdoor.com/role/NetLossPerShareAttributabletoCommonStockholdersComputationofBasicandDilutedNetLossPerShareDetails" xlink:type="simple" xlink:href="nxdr-20250930.xsd#NetLossPerShareAttributabletoCommonStockholdersComputationofBasicandDilutedNetLossPerShareDetails"/>
  <link:definitionLink xlink:role="http://www.nextdoor.com/role/NetLossPerShareAttributabletoCommonStockholdersComputationofBasicandDilutedNetLossPerShareDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasicLineItems_faaab5f9-83ac-46cd-a910-a32ae1bab6d6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EarningsPerShareBasicLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEarningsPerShareBasicByCommonClassTable_12e9a9cf-c41d-46ef-9abd-9553f5a928d7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfEarningsPerShareBasicByCommonClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EarningsPerShareBasicLineItems_faaab5f9-83ac-46cd-a910-a32ae1bab6d6" xlink:to="loc_us-gaap_ScheduleOfEarningsPerShareBasicByCommonClassTable_12e9a9cf-c41d-46ef-9abd-9553f5a928d7" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_7e8dca1e-cde6-440e-b6a2-fed27241ea74" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEarningsPerShareBasicByCommonClassTable_12e9a9cf-c41d-46ef-9abd-9553f5a928d7" xlink:to="loc_us-gaap_StatementClassOfStockAxis_7e8dca1e-cde6-440e-b6a2-fed27241ea74" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_7e8dca1e-cde6-440e-b6a2-fed27241ea74_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_7e8dca1e-cde6-440e-b6a2-fed27241ea74" xlink:to="loc_us-gaap_ClassOfStockDomain_7e8dca1e-cde6-440e-b6a2-fed27241ea74_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_a731ccc3-281f-44fa-9171-5979c2f00d7b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_7e8dca1e-cde6-440e-b6a2-fed27241ea74" xlink:to="loc_us-gaap_ClassOfStockDomain_a731ccc3-281f-44fa-9171-5979c2f00d7b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_c8895f2c-9185-46b6-8adc-2be62f38b56d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_a731ccc3-281f-44fa-9171-5979c2f00d7b" xlink:to="loc_us-gaap_CommonClassAMember_c8895f2c-9185-46b6-8adc-2be62f38b56d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassBMember_f0ef2def-5c2b-4beb-b836-857d074f3126" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonClassBMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_a731ccc3-281f-44fa-9171-5979c2f00d7b" xlink:to="loc_us-gaap_CommonClassBMember_f0ef2def-5c2b-4beb-b836-857d074f3126" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic_31ce2eb7-0ae1-40b8-a1c3-eca668cad982" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicLineItems_faaab5f9-83ac-46cd-a910-a32ae1bab6d6" xlink:to="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic_31ce2eb7-0ae1-40b8-a1c3-eca668cad982" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted_4da67d8d-2e06-4e78-992e-86fe63f303c2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicLineItems_faaab5f9-83ac-46cd-a910-a32ae1bab6d6" xlink:to="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted_4da67d8d-2e06-4e78-992e-86fe63f303c2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_002c7a8f-a2a8-414a-9042-668f74442bc6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicLineItems_faaab5f9-83ac-46cd-a910-a32ae1bab6d6" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_002c7a8f-a2a8-414a-9042-668f74442bc6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_b0e1c33e-7697-4778-bb8c-b5b382f0c93b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicLineItems_faaab5f9-83ac-46cd-a910-a32ae1bab6d6" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_b0e1c33e-7697-4778-bb8c-b5b382f0c93b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic_fd0451dd-6553-4cb0-ad67-fd28f09b7b58" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EarningsPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicLineItems_faaab5f9-83ac-46cd-a910-a32ae1bab6d6" xlink:to="loc_us-gaap_EarningsPerShareBasic_fd0451dd-6553-4cb0-ad67-fd28f09b7b58" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_55ff9d74-d5a3-44cd-8637-ae8149077a58" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicLineItems_faaab5f9-83ac-46cd-a910-a32ae1bab6d6" xlink:to="loc_us-gaap_EarningsPerShareDiluted_55ff9d74-d5a3-44cd-8637-ae8149077a58" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nextdoor.com/role/NetLossPerShareAttributabletoCommonStockholdersPotentiallyDilutiveSecuritiesOutstandingDetails" xlink:type="simple" xlink:href="nxdr-20250930.xsd#NetLossPerShareAttributabletoCommonStockholdersPotentiallyDilutiveSecuritiesOutstandingDetails"/>
  <link:definitionLink xlink:role="http://www.nextdoor.com/role/NetLossPerShareAttributabletoCommonStockholdersPotentiallyDilutiveSecuritiesOutstandingDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_ad18d354-3448-4625-9f01-523277d662b2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_93f5a6cd-099f-418f-bfeb-4ad4951a2f1c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_ad18d354-3448-4625-9f01-523277d662b2" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_93f5a6cd-099f-418f-bfeb-4ad4951a2f1c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_3082e8ef-dd3c-4ca4-85f5-40dcf4c8c05c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_93f5a6cd-099f-418f-bfeb-4ad4951a2f1c" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_3082e8ef-dd3c-4ca4-85f5-40dcf4c8c05c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_3082e8ef-dd3c-4ca4-85f5-40dcf4c8c05c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_3082e8ef-dd3c-4ca4-85f5-40dcf4c8c05c" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_3082e8ef-dd3c-4ca4-85f5-40dcf4c8c05c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_66e27dab-5d19-4a93-85af-84888e11d98f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_3082e8ef-dd3c-4ca4-85f5-40dcf4c8c05c" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_66e27dab-5d19-4a93-85af-84888e11d98f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_4e094341-db84-46e3-b666-1f151ce3edb9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_66e27dab-5d19-4a93-85af-84888e11d98f" xlink:to="loc_us-gaap_EmployeeStockOptionMember_4e094341-db84-46e3-b666-1f151ce3edb9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_b6ce460b-ee76-46b3-91b0-b9fde449351e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_66e27dab-5d19-4a93-85af-84888e11d98f" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_b6ce460b-ee76-46b3-91b0-b9fde449351e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nxdr_EmployeeStockPurchasePlanMember_a26a067d-4e13-4eae-9b7f-36879b248941" xlink:href="nxdr-20250930.xsd#nxdr_EmployeeStockPurchasePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_66e27dab-5d19-4a93-85af-84888e11d98f" xlink:to="loc_nxdr_EmployeeStockPurchasePlanMember_a26a067d-4e13-4eae-9b7f-36879b248941" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_de894c24-7ff6-469d-950a-05dc67859f3a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_ad18d354-3448-4625-9f01-523277d662b2" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_de894c24-7ff6-469d-950a-05dc67859f3a" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nextdoor.com/role/SegmentandGeographicalInformationDetails" xlink:type="simple" xlink:href="nxdr-20250930.xsd#SegmentandGeographicalInformationDetails"/>
  <link:definitionLink xlink:role="http://www.nextdoor.com/role/SegmentandGeographicalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_0699a5e3-df85-49db-bfd9-a3501871a235" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_1a0bd99c-7976-4dd1-b8bb-3f0111d68d42" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_0699a5e3-df85-49db-bfd9-a3501871a235" xlink:to="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_1a0bd99c-7976-4dd1-b8bb-3f0111d68d42" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_8f6b4462-7dce-4851-85e7-3f9dfb5a2bab" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_1a0bd99c-7976-4dd1-b8bb-3f0111d68d42" xlink:to="loc_srt_StatementGeographicalAxis_8f6b4462-7dce-4851-85e7-3f9dfb5a2bab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_8f6b4462-7dce-4851-85e7-3f9dfb5a2bab_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_8f6b4462-7dce-4851-85e7-3f9dfb5a2bab" xlink:to="loc_srt_SegmentGeographicalDomain_8f6b4462-7dce-4851-85e7-3f9dfb5a2bab_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_7a49fcc9-edf3-42dd-be14-f90cdfadc1a8" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_8f6b4462-7dce-4851-85e7-3f9dfb5a2bab" xlink:to="loc_srt_SegmentGeographicalDomain_7a49fcc9-edf3-42dd-be14-f90cdfadc1a8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_2dd975cf-feec-4711-bb55-9167458b6af5" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_7a49fcc9-edf3-42dd-be14-f90cdfadc1a8" xlink:to="loc_country_US_2dd975cf-feec-4711-bb55-9167458b6af5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonUsMember_53afe91a-2c78-4a98-a277-fe630534d366" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NonUsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_7a49fcc9-edf3-42dd-be14-f90cdfadc1a8" xlink:to="loc_us-gaap_NonUsMember_53afe91a-2c78-4a98-a277-fe630534d366" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_77def6ba-a1a2-4ec3-8fd6-ef4c35716329" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_0699a5e3-df85-49db-bfd9-a3501871a235" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_77def6ba-a1a2-4ec3-8fd6-ef4c35716329" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nextdoor.com/role/RestructuringScheduleofRestructuringChargesDetails" xlink:type="simple" xlink:href="nxdr-20250930.xsd#RestructuringScheduleofRestructuringChargesDetails"/>
  <link:definitionLink xlink:role="http://www.nextdoor.com/role/RestructuringScheduleofRestructuringChargesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_6a570850-a130-4241-9b47-4e0805d63849" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringCostAndReserveLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_db5ea7e0-2183-4e65-88de-9f26937202ee" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_6a570850-a130-4241-9b47-4e0805d63849" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_db5ea7e0-2183-4e65-88de-9f26937202ee" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanAxis_d4cf9db6-9521-4c96-9b3f-507d1ad0afe7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringPlanAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_db5ea7e0-2183-4e65-88de-9f26937202ee" xlink:to="loc_us-gaap_RestructuringPlanAxis_d4cf9db6-9521-4c96-9b3f-507d1ad0afe7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanDomain_d4cf9db6-9521-4c96-9b3f-507d1ad0afe7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringPlanAxis_d4cf9db6-9521-4c96-9b3f-507d1ad0afe7" xlink:to="loc_us-gaap_RestructuringPlanDomain_d4cf9db6-9521-4c96-9b3f-507d1ad0afe7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanDomain_e3522f63-4585-415c-bf50-af13e818fddd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringPlanAxis_d4cf9db6-9521-4c96-9b3f-507d1ad0afe7" xlink:to="loc_us-gaap_RestructuringPlanDomain_e3522f63-4585-415c-bf50-af13e818fddd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nxdr_CostReductionPlanMember_cc4d12d2-b93f-44e7-921b-d37d339cb2f3" xlink:href="nxdr-20250930.xsd#nxdr_CostReductionPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringPlanDomain_e3522f63-4585-415c-bf50-af13e818fddd" xlink:to="loc_nxdr_CostReductionPlanMember_cc4d12d2-b93f-44e7-921b-d37d339cb2f3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_6db8929e-f33f-4af6-9840-6f781fbf3b64" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_db5ea7e0-2183-4e65-88de-9f26937202ee" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_6db8929e-f33f-4af6-9840-6f781fbf3b64" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_6db8929e-f33f-4af6-9840-6f781fbf3b64_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_6db8929e-f33f-4af6-9840-6f781fbf3b64" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_6db8929e-f33f-4af6-9840-6f781fbf3b64_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_2059b09e-777a-4fe8-84da-6105624bddd6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_6db8929e-f33f-4af6-9840-6f781fbf3b64" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_2059b09e-777a-4fe8-84da-6105624bddd6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpenseMember_e5e0ed44-9271-4d3d-8e75-adcc3bc2acc8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ResearchAndDevelopmentExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_2059b09e-777a-4fe8-84da-6105624bddd6" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpenseMember_e5e0ed44-9271-4d3d-8e75-adcc3bc2acc8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingAndMarketingExpenseMember_1fd68100-5d5e-48b6-a83e-ed3e949f5e20" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SellingAndMarketingExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_2059b09e-777a-4fe8-84da-6105624bddd6" xlink:to="loc_us-gaap_SellingAndMarketingExpenseMember_1fd68100-5d5e-48b6-a83e-ed3e949f5e20" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpenseMember_b10dce86-55a8-436d-b88c-74845a666866" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GeneralAndAdministrativeExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_2059b09e-777a-4fe8-84da-6105624bddd6" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpenseMember_b10dce86-55a8-436d-b88c-74845a666866" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveAxis_541ddfa3-fe67-4001-a05b-796e7cae1dfd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringCostAndReserveAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_db5ea7e0-2183-4e65-88de-9f26937202ee" xlink:to="loc_us-gaap_RestructuringCostAndReserveAxis_541ddfa3-fe67-4001-a05b-796e7cae1dfd" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_541ddfa3-fe67-4001-a05b-796e7cae1dfd_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_541ddfa3-fe67-4001-a05b-796e7cae1dfd" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_541ddfa3-fe67-4001-a05b-796e7cae1dfd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_1805c059-4f88-460e-8293-83119a9ec89a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_541ddfa3-fe67-4001-a05b-796e7cae1dfd" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_1805c059-4f88-460e-8293-83119a9ec89a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeSeveranceMember_840d20c3-308b-47aa-b66e-a8c1526215ae" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeSeveranceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_1805c059-4f88-460e-8293-83119a9ec89a" xlink:to="loc_us-gaap_EmployeeSeveranceMember_840d20c3-308b-47aa-b66e-a8c1526215ae" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCharges_56189fa6-980d-411a-bfe8-44bb33d67ff3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_6a570850-a130-4241-9b47-4e0805d63849" xlink:to="loc_us-gaap_RestructuringCharges_56189fa6-980d-411a-bfe8-44bb33d67ff3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_ada9480e-fa3c-424f-b00d-a7a60d5779e5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_6a570850-a130-4241-9b47-4e0805d63849" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_ada9480e-fa3c-424f-b00d-a7a60d5779e5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nxdr_OfficeSpaceReductions_75df8132-3f56-43fa-b675-50e4f02ed500" xlink:href="nxdr-20250930.xsd#nxdr_OfficeSpaceReductions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_6a570850-a130-4241-9b47-4e0805d63849" xlink:to="loc_nxdr_OfficeSpaceReductions_75df8132-3f56-43fa-b675-50e4f02ed500" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCosts_ddc2f8d3-15e9-4877-86e5-bab02b0fc617" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_6a570850-a130-4241-9b47-4e0805d63849" xlink:to="loc_us-gaap_RestructuringCosts_ddc2f8d3-15e9-4877-86e5-bab02b0fc617" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nextdoor.com/role/RestructuringNarrativeDetails" xlink:type="simple" xlink:href="nxdr-20250930.xsd#RestructuringNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.nextdoor.com/role/RestructuringNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_30fc9ae4-0600-4d6a-85e1-9b681be6b057" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringCostAndReserveLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_59c63532-9de7-431c-8c4d-bf39f710154f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_30fc9ae4-0600-4d6a-85e1-9b681be6b057" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_59c63532-9de7-431c-8c4d-bf39f710154f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveAxis_25a11fb2-6128-43f6-b48c-16969f0a3f20" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringCostAndReserveAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_59c63532-9de7-431c-8c4d-bf39f710154f" xlink:to="loc_us-gaap_RestructuringCostAndReserveAxis_25a11fb2-6128-43f6-b48c-16969f0a3f20" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_25a11fb2-6128-43f6-b48c-16969f0a3f20_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_25a11fb2-6128-43f6-b48c-16969f0a3f20" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_25a11fb2-6128-43f6-b48c-16969f0a3f20_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_cf75b9f7-a598-4c78-bd6c-9933d9df8692" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_25a11fb2-6128-43f6-b48c-16969f0a3f20" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_cf75b9f7-a598-4c78-bd6c-9933d9df8692" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeSeveranceMember_4531ba08-4714-4c2a-99aa-d09ba43458d9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeSeveranceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_cf75b9f7-a598-4c78-bd6c-9933d9df8692" xlink:to="loc_us-gaap_EmployeeSeveranceMember_4531ba08-4714-4c2a-99aa-d09ba43458d9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanAxis_d36a72fb-66cc-4469-ac88-700254f887da" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringPlanAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_59c63532-9de7-431c-8c4d-bf39f710154f" xlink:to="loc_us-gaap_RestructuringPlanAxis_d36a72fb-66cc-4469-ac88-700254f887da" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanDomain_d36a72fb-66cc-4469-ac88-700254f887da_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringPlanAxis_d36a72fb-66cc-4469-ac88-700254f887da" xlink:to="loc_us-gaap_RestructuringPlanDomain_d36a72fb-66cc-4469-ac88-700254f887da_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanDomain_69e7c058-354e-44bc-82ab-e3c7b92c9877" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringPlanAxis_d36a72fb-66cc-4469-ac88-700254f887da" xlink:to="loc_us-gaap_RestructuringPlanDomain_69e7c058-354e-44bc-82ab-e3c7b92c9877" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nxdr_CostReductionPlanMember_614a5fdb-1ded-4be7-a7d8-9661bac715b1" xlink:href="nxdr-20250930.xsd#nxdr_CostReductionPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringPlanDomain_69e7c058-354e-44bc-82ab-e3c7b92c9877" xlink:to="loc_nxdr_CostReductionPlanMember_614a5fdb-1ded-4be7-a7d8-9661bac715b1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringReserve_6a26121f-d4c2-4f42-aba0-676c42a95603" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringReserve"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_30fc9ae4-0600-4d6a-85e1-9b681be6b057" xlink:to="loc_us-gaap_RestructuringReserve_6a26121f-d4c2-4f42-aba0-676c42a95603" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminated_abbf61ad-c1d4-4692-997c-be1a94ffca26" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminated"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_30fc9ae4-0600-4d6a-85e1-9b681be6b057" xlink:to="loc_us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminated_abbf61ad-c1d4-4692-997c-be1a94ffca26" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCharges_281fabfe-2c81-4b3e-a182-edfb24a79d64" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_30fc9ae4-0600-4d6a-85e1-9b681be6b057" xlink:to="loc_us-gaap_RestructuringCharges_281fabfe-2c81-4b3e-a182-edfb24a79d64" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nxdr_OfficeSpaceReductions_85c92b27-c236-45ee-8507-fbebb0175f20" xlink:href="nxdr-20250930.xsd#nxdr_OfficeSpaceReductions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_30fc9ae4-0600-4d6a-85e1-9b681be6b057" xlink:to="loc_nxdr_OfficeSpaceReductions_85c92b27-c236-45ee-8507-fbebb0175f20" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://xbrl.sec.gov/ecd/role/IndividualsOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/ecd/2025/ecd-2025.xsd#IndividualsOnly"/>
  <link:definitionLink xlink:role="http://xbrl.sec.gov/ecd/role/IndividualsOnly" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ecd_AllIndividualsMember" xlink:href="https://xbrl.sec.gov/ecd/2025/ecd-2025.xsd#ecd_AllIndividualsMember"/>
    <link:loc xlink:type="locator" xlink:label="loc_nxdr_SophiaSchwartzMember_38dd7227-6c0d-400f-a4cc-de9ec5c7fd96" xlink:href="nxdr-20250930.xsd#nxdr_SophiaSchwartzMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ecd_AllIndividualsMember" xlink:to="loc_nxdr_SophiaSchwartzMember_38dd7227-6c0d-400f-a4cc-de9ec5c7fd96" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nxdr_CraigLisowskiMember_6d9c18f5-3a0a-4722-80dc-7d9601ac02a8" xlink:href="nxdr-20250930.xsd#nxdr_CraigLisowskiMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ecd_AllIndividualsMember" xlink:to="loc_nxdr_CraigLisowskiMember_6d9c18f5-3a0a-4722-80dc-7d9601ac02a8" xlink:type="arc" order="3"/>
  </link:definitionLink>
</link:linkbase>
