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

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:019e663d-5ef2-783f-ae07-33965fe35d9b,g:cc369daf-edf4-41b5-ab75-265141237f0c-->
<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.waystar.com/role/UnauditedCondensedConsolidatedBalanceSheets" xlink:type="simple" xlink:href="way-20260630.xsd#UnauditedCondensedConsolidatedBalanceSheets"/>
  <link:definitionLink xlink:role="http://www.waystar.com/role/UnauditedCondensedConsolidatedBalanceSheets" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019e663d-6092-7321-9ef9-021a08d1361f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019e663d-6092-79ba-b030-a69752c434f4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019e663d-6092-7321-9ef9-021a08d1361f" xlink:to="loc_us-gaap_StatementTable_019e663d-6092-79ba-b030-a69752c434f4" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019e663d-6092-7469-a9e6-e5c1c8f830b0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019e663d-6092-79ba-b030-a69752c434f4" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019e663d-6092-7469-a9e6-e5c1c8f830b0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_019e663d-6092-7469-a9e6-e5c1c8f830b0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019e663d-6092-7469-a9e6-e5c1c8f830b0" xlink:to="loc_us-gaap_RelatedPartyDomain_019e663d-6092-7469-a9e6-e5c1c8f830b0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_019e663d-6092-7c21-927a-49904f1f8dc5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019e663d-6092-7469-a9e6-e5c1c8f830b0" xlink:to="loc_us-gaap_RelatedPartyDomain_019e663d-6092-7c21-927a-49904f1f8dc5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonrelatedPartyMember_019e663d-6092-711f-8814-5c1621531864" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NonrelatedPartyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_019e663d-6092-7c21-927a-49904f1f8dc5" xlink:to="loc_us-gaap_NonrelatedPartyMember_019e663d-6092-711f-8814-5c1621531864" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyMember_019e663d-6092-7549-8f5d-9ce5ea322e9d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_019e663d-6092-7c21-927a-49904f1f8dc5" xlink:to="loc_us-gaap_RelatedPartyMember_019e663d-6092-7549-8f5d-9ce5ea322e9d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsAbstract_019e663d-6092-75ec-afbf-9ec7db661b80" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e663d-6092-7321-9ef9-021a08d1361f" xlink:to="loc_us-gaap_AssetsAbstract_019e663d-6092-75ec-afbf-9ec7db661b80" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrentAbstract_019e663d-6092-77cc-8184-a82b10398686" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsCurrentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019e663d-6092-75ec-afbf-9ec7db661b80" xlink:to="loc_us-gaap_AssetsCurrentAbstract_019e663d-6092-77cc-8184-a82b10398686" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_019e663d-6092-7e38-80fd-7322c43f5041" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_019e663d-6092-77cc-8184-a82b10398686" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_019e663d-6092-7e38-80fd-7322c43f5041" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashCurrent_019e663d-6092-7716-8e86-6ecaf99f0f7f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestrictedCashCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_019e663d-6092-77cc-8184-a82b10398686" xlink:to="loc_us-gaap_RestrictedCashCurrent_019e663d-6092-7716-8e86-6ecaf99f0f7f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecuritiesCurrent_019e663d-6092-7c93-a8f3-3891990e66f7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecuritiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_019e663d-6092-77cc-8184-a82b10398686" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecuritiesCurrent_019e663d-6092-7c93-a8f3-3891990e66f7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableNetCurrent_019e663d-6092-70ad-93ce-31554aadc7b9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccountsReceivableNetCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_019e663d-6092-77cc-8184-a82b10398686" xlink:to="loc_us-gaap_AccountsReceivableNetCurrent_019e663d-6092-70ad-93ce-31554aadc7b9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxesReceivable_019e663d-6092-7a2b-b32a-f2bfecec513e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxesReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_019e663d-6092-77cc-8184-a82b10398686" xlink:to="loc_us-gaap_IncomeTaxesReceivable_019e663d-6092-7a2b-b32a-f2bfecec513e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrepaidExpenseCurrent_019e663d-6092-73c4-a93e-bf5ae3003d77" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PrepaidExpenseCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_019e663d-6092-77cc-8184-a82b10398686" xlink:to="loc_us-gaap_PrepaidExpenseCurrent_019e663d-6092-73c4-a93e-bf5ae3003d77" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsCurrent_019e663d-6092-7104-ae49-10ca0c0ea8bd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherAssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_019e663d-6092-77cc-8184-a82b10398686" xlink:to="loc_us-gaap_OtherAssetsCurrent_019e663d-6092-7104-ae49-10ca0c0ea8bd" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrent_019e663d-6092-759f-9ae2-3c8c1068c0c7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_019e663d-6092-77cc-8184-a82b10398686" xlink:to="loc_us-gaap_AssetsCurrent_019e663d-6092-759f-9ae2-3c8c1068c0c7" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_019e663d-6092-7a89-9555-fc4c99cc978a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019e663d-6092-75ec-afbf-9ec7db661b80" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_019e663d-6092-7a89-9555-fc4c99cc978a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset_019e663d-6092-71b2-9d43-27bc610ab36e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingLeaseRightOfUseAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019e663d-6092-75ec-afbf-9ec7db661b80" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAsset_019e663d-6092-71b2-9d43-27bc610ab36e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_019e663d-6092-7d22-abbd-e351b4e1e321" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019e663d-6092-75ec-afbf-9ec7db661b80" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_019e663d-6092-7d22-abbd-e351b4e1e321" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_019e663d-6092-7bf7-bd8f-900d055400f2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019e663d-6092-75ec-afbf-9ec7db661b80" xlink:to="loc_us-gaap_Goodwill_019e663d-6092-7bf7-bd8f-900d055400f2" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCosts_019e663d-6092-702c-948e-1b6454e6d204" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DeferredCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019e663d-6092-75ec-afbf-9ec7db661b80" xlink:to="loc_us-gaap_DeferredCosts_019e663d-6092-702c-948e-1b6454e6d204" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsNoncurrent_019e663d-6092-77f4-9618-9701867ff4f5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherAssetsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019e663d-6092-75ec-afbf-9ec7db661b80" xlink:to="loc_us-gaap_OtherAssetsNoncurrent_019e663d-6092-77f4-9618-9701867ff4f5" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_019e663d-6092-7770-a663-468ed0518522" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019e663d-6092-75ec-afbf-9ec7db661b80" xlink:to="loc_us-gaap_Assets_019e663d-6092-7770-a663-468ed0518522" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019e663d-6092-732b-be1d-11d615e1a0c6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesAndStockholdersEquityAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e663d-6092-7321-9ef9-021a08d1361f" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019e663d-6092-732b-be1d-11d615e1a0c6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrentAbstract_019e663d-6092-77e0-adeb-d579740afd87" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesCurrentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019e663d-6092-732b-be1d-11d615e1a0c6" xlink:to="loc_us-gaap_LiabilitiesCurrentAbstract_019e663d-6092-77e0-adeb-d579740afd87" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableCurrent_019e663d-6092-7e5d-a446-570a2f393e33" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccountsPayableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019e663d-6092-77e0-adeb-d579740afd87" xlink:to="loc_us-gaap_AccountsPayableCurrent_019e663d-6092-7e5d-a446-570a2f393e33" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeRelatedLiabilitiesCurrent_019e663d-6092-7a9a-b2cf-aa9edfccf8e9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeRelatedLiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019e663d-6092-77e0-adeb-d579740afd87" xlink:to="loc_us-gaap_EmployeeRelatedLiabilitiesCurrent_019e663d-6092-7a9a-b2cf-aa9edfccf8e9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_way_AggregatedFundsPayableCurrent_019e663d-6092-734c-bd79-8bb0cb059b31" xlink:href="way-20260630.xsd#way_AggregatedFundsPayableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019e663d-6092-77e0-adeb-d579740afd87" xlink:to="loc_way_AggregatedFundsPayableCurrent_019e663d-6092-734c-bd79-8bb0cb059b31" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAccruedLiabilitiesCurrent_019e663d-6092-76e2-8b23-24e98c0aa426" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherAccruedLiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019e663d-6092-77e0-adeb-d579740afd87" xlink:to="loc_us-gaap_OtherAccruedLiabilitiesCurrent_019e663d-6092-76e2-8b23-24e98c0aa426" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityCurrent_019e663d-6092-7d23-9115-2aa9f83aba37" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ContractWithCustomerLiabilityCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019e663d-6092-77e0-adeb-d579740afd87" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityCurrent_019e663d-6092-7d23-9115-2aa9f83aba37" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtCurrent_019e663d-6092-7329-8c26-1c9f98d5afae" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebtCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019e663d-6092-77e0-adeb-d579740afd87" xlink:to="loc_us-gaap_LongTermDebtCurrent_019e663d-6092-7329-8c26-1c9f98d5afae" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityCurrent_019e663d-6092-7e04-ac79-ac3ced5724ba" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingLeaseLiabilityCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019e663d-6092-77e0-adeb-d579740afd87" xlink:to="loc_us-gaap_OperatingLeaseLiabilityCurrent_019e663d-6092-7e04-ac79-ac3ced5724ba" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrent_019e663d-6092-7526-ae31-ca6cb98aedae" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019e663d-6092-77e0-adeb-d579740afd87" xlink:to="loc_us-gaap_LiabilitiesCurrent_019e663d-6092-7526-ae31-ca6cb98aedae" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesNoncurrentAbstract_019e663d-6092-7326-ab68-2a724afb62e0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesNoncurrentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019e663d-6092-732b-be1d-11d615e1a0c6" xlink:to="loc_us-gaap_LiabilitiesNoncurrentAbstract_019e663d-6092-7326-ab68-2a724afb62e0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet_019e663d-6092-7dee-8c01-edc78107c893" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DeferredIncomeTaxLiabilitiesNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesNoncurrentAbstract_019e663d-6092-7326-ab68-2a724afb62e0" xlink:to="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet_019e663d-6092-7dee-8c01-edc78107c893" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtNoncurrent_019e663d-6092-7397-a3ce-602ba909be0b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebtNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesNoncurrentAbstract_019e663d-6092-7326-ab68-2a724afb62e0" xlink:to="loc_us-gaap_LongTermDebtNoncurrent_019e663d-6092-7397-a3ce-602ba909be0b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_019e663d-6092-73da-bc02-3556d421f5b7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingLeaseLiabilityNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesNoncurrentAbstract_019e663d-6092-7326-ab68-2a724afb62e0" xlink:to="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_019e663d-6092-73da-bc02-3556d421f5b7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityNoncurrent_019e663d-6092-72e0-943f-5655672d0b2e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ContractWithCustomerLiabilityNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesNoncurrentAbstract_019e663d-6092-7326-ab68-2a724afb62e0" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityNoncurrent_019e663d-6092-72e0-943f-5655672d0b2e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilitiesNoncurrent_019e663d-6092-7e10-909b-3715421b51e9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherLiabilitiesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesNoncurrentAbstract_019e663d-6092-7326-ab68-2a724afb62e0" xlink:to="loc_us-gaap_OtherLiabilitiesNoncurrent_019e663d-6092-7e10-909b-3715421b51e9" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Liabilities_019e663d-6092-762f-900f-f217bece995b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Liabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesNoncurrentAbstract_019e663d-6092-7326-ab68-2a724afb62e0" xlink:to="loc_us-gaap_Liabilities_019e663d-6092-762f-900f-f217bece995b" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommitmentsAndContingencies_019e663d-6092-72af-829c-5e7f8673a4d6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommitmentsAndContingencies"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019e663d-6092-732b-be1d-11d615e1a0c6" xlink:to="loc_us-gaap_CommitmentsAndContingencies_019e663d-6092-72af-829c-5e7f8673a4d6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityAbstract_019e663d-6092-7dd6-8968-4f691b35ce4d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquityAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019e663d-6092-732b-be1d-11d615e1a0c6" xlink:to="loc_us-gaap_StockholdersEquityAbstract_019e663d-6092-7dd6-8968-4f691b35ce4d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockValue_019e663d-6092-789b-9e79-5249e329bf55" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_019e663d-6092-7dd6-8968-4f691b35ce4d" xlink:to="loc_us-gaap_PreferredStockValue_019e663d-6092-789b-9e79-5249e329bf55" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockValue_019e663d-6092-7697-8354-14eb8b9c5c9d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_019e663d-6092-7dd6-8968-4f691b35ce4d" xlink:to="loc_us-gaap_CommonStockValue_019e663d-6092-7697-8354-14eb8b9c5c9d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonValue_019edde7-b5d9-7104-8aa7-13699d52729d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TreasuryStockCommonValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_019e663d-6092-7dd6-8968-4f691b35ce4d" xlink:to="loc_us-gaap_TreasuryStockCommonValue_019edde7-b5d9-7104-8aa7-13699d52729d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapital_019e663d-6092-7ce3-9d7d-017eb7fcaafd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdditionalPaidInCapital"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_019e663d-6092-7dd6-8968-4f691b35ce4d" xlink:to="loc_us-gaap_AdditionalPaidInCapital_019e663d-6092-7ce3-9d7d-017eb7fcaafd" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_019e663d-6092-73a5-8840-f044de739b63" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_019e663d-6092-7dd6-8968-4f691b35ce4d" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_019e663d-6092-73a5-8840-f044de739b63" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_019e663d-6092-71d1-94cb-1399b0904eff" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RetainedEarningsAccumulatedDeficit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_019e663d-6092-7dd6-8968-4f691b35ce4d" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_019e663d-6092-71d1-94cb-1399b0904eff" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019e663d-6092-7c97-82b2-c28fd7bb932a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_019e663d-6092-7dd6-8968-4f691b35ce4d" xlink:to="loc_us-gaap_StockholdersEquity_019e663d-6092-7c97-82b2-c28fd7bb932a" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity_019e663d-6092-7ff9-9b8b-d7caff1e1218" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesAndStockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019e663d-6092-732b-be1d-11d615e1a0c6" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquity_019e663d-6092-7ff9-9b8b-d7caff1e1218" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.waystar.com/role/UnauditedCondensedConsolidatedStatementsofOperations" xlink:type="simple" xlink:href="way-20260630.xsd#UnauditedCondensedConsolidatedStatementsofOperations"/>
  <link:definitionLink xlink:role="http://www.waystar.com/role/UnauditedCondensedConsolidatedStatementsofOperations" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019e663d-6092-763d-9cf6-57689246241c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019e663d-6092-70b9-99c0-baf68831f436" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019e663d-6092-763d-9cf6-57689246241c" xlink:to="loc_us-gaap_StatementTable_019e663d-6092-70b9-99c0-baf68831f436" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019e663d-6092-789c-9ede-ab0d7fef539b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019e663d-6092-70b9-99c0-baf68831f436" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019e663d-6092-789c-9ede-ab0d7fef539b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_019e663d-6092-789c-9ede-ab0d7fef539b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019e663d-6092-789c-9ede-ab0d7fef539b" xlink:to="loc_us-gaap_RelatedPartyDomain_019e663d-6092-789c-9ede-ab0d7fef539b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_019e663d-6092-726f-9e33-704734c000c9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019e663d-6092-789c-9ede-ab0d7fef539b" xlink:to="loc_us-gaap_RelatedPartyDomain_019e663d-6092-726f-9e33-704734c000c9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonrelatedPartyMember_019e663d-6092-719b-8497-1ace1965f5f7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NonrelatedPartyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_019e663d-6092-726f-9e33-704734c000c9" xlink:to="loc_us-gaap_NonrelatedPartyMember_019e663d-6092-719b-8497-1ace1965f5f7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyMember_019e663d-6092-7720-aff4-8201c3383b12" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_019e663d-6092-726f-9e33-704734c000c9" xlink:to="loc_us-gaap_RelatedPartyMember_019e663d-6092-7720-aff4-8201c3383b12" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019e663d-6092-7e78-8b5c-2b30d007de67" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e663d-6092-763d-9cf6-57689246241c" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019e663d-6092-7e78-8b5c-2b30d007de67" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostsAndExpensesAbstract_019e663d-6092-7125-aa77-1f355328acae" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CostsAndExpensesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e663d-6092-763d-9cf6-57689246241c" xlink:to="loc_us-gaap_CostsAndExpensesAbstract_019e663d-6092-7125-aa77-1f355328acae" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfGoodsAndServiceExcludingDepreciationDepletionAndAmortization_019e663d-6092-7b4a-a498-694243c9e565" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CostOfGoodsAndServiceExcludingDepreciationDepletionAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_019e663d-6092-7125-aa77-1f355328acae" xlink:to="loc_us-gaap_CostOfGoodsAndServiceExcludingDepreciationDepletionAndAmortization_019e663d-6092-7b4a-a498-694243c9e565" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingAndMarketingExpense_019e663d-6092-743f-a35c-e81966f071c2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SellingAndMarketingExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_019e663d-6092-7125-aa77-1f355328acae" xlink:to="loc_us-gaap_SellingAndMarketingExpense_019e663d-6092-743f-a35c-e81966f071c2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpense_019e663d-6092-7516-a938-43c7313e6625" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_019e663d-6092-7125-aa77-1f355328acae" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpense_019e663d-6092-7516-a938-43c7313e6625" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpense_019e663d-6092-7852-a41b-3d311407b5a1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ResearchAndDevelopmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_019e663d-6092-7125-aa77-1f355328acae" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpense_019e663d-6092-7852-a41b-3d311407b5a1" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepreciationAndAmortization_019e663d-6092-70eb-8535-3c8749d60ae4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_019e663d-6092-7125-aa77-1f355328acae" xlink:to="loc_us-gaap_DepreciationAndAmortization_019e663d-6092-70eb-8535-3c8749d60ae4" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostsAndExpenses_019e663d-6092-786e-8d37-b43cae9f4d19" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CostsAndExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_019e663d-6092-7125-aa77-1f355328acae" xlink:to="loc_us-gaap_CostsAndExpenses_019e663d-6092-786e-8d37-b43cae9f4d19" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_019e663d-6092-7b2f-9a44-e1fbed399560" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e663d-6092-763d-9cf6-57689246241c" xlink:to="loc_us-gaap_OperatingIncomeLoss_019e663d-6092-7b2f-9a44-e1fbed399560" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpenseAbstract_019e663d-6092-7df1-bb0c-5a0bdf56bcfc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherNonoperatingIncomeExpenseAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e663d-6092-763d-9cf6-57689246241c" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpenseAbstract_019e663d-6092-7df1-bb0c-5a0bdf56bcfc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseNonoperating_019e663d-6092-7c07-bb6f-bea3a7f2246a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestExpenseNonoperating"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherNonoperatingIncomeExpenseAbstract_019e663d-6092-7df1-bb0c-5a0bdf56bcfc" xlink:to="loc_us-gaap_InterestExpenseNonoperating_019e663d-6092-7c07-bb6f-bea3a7f2246a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_019e663d-6092-7557-be34-896dd415d309" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e663d-6092-763d-9cf6-57689246241c" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_019e663d-6092-7557-be34-896dd415d309" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_019e663d-6092-7665-bfac-91734a5dd0f1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e663d-6092-763d-9cf6-57689246241c" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_019e663d-6092-7665-bfac-91734a5dd0f1" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019e663d-6092-7a8a-b645-9c35f4182ce4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e663d-6092-763d-9cf6-57689246241c" xlink:to="loc_us-gaap_NetIncomeLoss_019e663d-6092-7a8a-b645-9c35f4182ce4" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareAbstract_019e663d-6092-7986-8280-e51362f31a2c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EarningsPerShareAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e663d-6092-763d-9cf6-57689246241c" xlink:to="loc_us-gaap_EarningsPerShareAbstract_019e663d-6092-7986-8280-e51362f31a2c" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic_019e663d-6092-734f-bfc2-db3858cfd2eb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EarningsPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareAbstract_019e663d-6092-7986-8280-e51362f31a2c" xlink:to="loc_us-gaap_EarningsPerShareBasic_019e663d-6092-734f-bfc2-db3858cfd2eb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_019e663d-6092-78e9-af6f-8c8cce331066" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareAbstract_019e663d-6092-7986-8280-e51362f31a2c" xlink:to="loc_us-gaap_EarningsPerShareDiluted_019e663d-6092-78e9-af6f-8c8cce331066" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_019e663d-6092-76dc-beff-b6bedd333208" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e663d-6092-763d-9cf6-57689246241c" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_019e663d-6092-76dc-beff-b6bedd333208" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_019e663d-6092-7f69-9e3b-6c0d5169899a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_019e663d-6092-76dc-beff-b6bedd333208" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_019e663d-6092-7f69-9e3b-6c0d5169899a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_019e663d-6092-7a53-939e-591b4aac4b2a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_019e663d-6092-76dc-beff-b6bedd333208" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_019e663d-6092-7a53-939e-591b4aac4b2a" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.waystar.com/role/UnauditedCondensedConsolidatedStatementsofChangesinStockholdersEquity" xlink:type="simple" xlink:href="way-20260630.xsd#UnauditedCondensedConsolidatedStatementsofChangesinStockholdersEquity"/>
  <link:definitionLink xlink:role="http://www.waystar.com/role/UnauditedCondensedConsolidatedStatementsofChangesinStockholdersEquity" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019e663d-6092-771f-8b5a-d68f6c77e631" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019e663d-6092-7341-896d-c2e83cdaca9d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019e663d-6092-771f-8b5a-d68f6c77e631" xlink:to="loc_us-gaap_StatementTable_019e663d-6092-7341-896d-c2e83cdaca9d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_019e663d-6092-731a-8f49-6d50da4203c1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019e663d-6092-7341-896d-c2e83cdaca9d" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_019e663d-6092-731a-8f49-6d50da4203c1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019e663d-6092-731a-8f49-6d50da4203c1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019e663d-6092-731a-8f49-6d50da4203c1" xlink:to="loc_us-gaap_EquityComponentDomain_019e663d-6092-731a-8f49-6d50da4203c1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019e663d-6092-769a-9326-f7f82bfc2c2c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019e663d-6092-731a-8f49-6d50da4203c1" xlink:to="loc_us-gaap_EquityComponentDomain_019e663d-6092-769a-9326-f7f82bfc2c2c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_019e663d-6092-72b4-9c68-f5764580dfb1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e663d-6092-769a-9326-f7f82bfc2c2c" xlink:to="loc_us-gaap_CommonStockMember_019e663d-6092-72b4-9c68-f5764580dfb1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonMember_019edde9-f06f-746e-bbde-a2dd0a563f72" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TreasuryStockCommonMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e663d-6092-769a-9326-f7f82bfc2c2c" xlink:to="loc_us-gaap_TreasuryStockCommonMember_019edde9-f06f-746e-bbde-a2dd0a563f72" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_019e663d-6092-7eb0-9a23-c9251742bb1b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e663d-6092-769a-9326-f7f82bfc2c2c" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_019e663d-6092-7eb0-9a23-c9251742bb1b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019e663d-6092-7633-9dd3-ed02bf22f341" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e663d-6092-769a-9326-f7f82bfc2c2c" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019e663d-6092-7633-9dd3-ed02bf22f341" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_019e663d-6092-76da-97ee-c9f4f2ce8cc3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e663d-6092-769a-9326-f7f82bfc2c2c" xlink:to="loc_us-gaap_RetainedEarningsMember_019e663d-6092-76da-97ee-c9f4f2ce8cc3" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e663d-6092-71a8-abc4-f82d61220f52" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e663d-6092-771f-8b5a-d68f6c77e631" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e663d-6092-71a8-abc4-f82d61220f52" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesOutstanding_019e663d-6092-7f70-8756-7ceac97a2282" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e663d-6092-71a8-abc4-f82d61220f52" xlink:to="loc_us-gaap_SharesOutstanding_019e663d-6092-7f70-8756-7ceac97a2282" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019e663d-6092-756c-8c64-e53c007b4333" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e663d-6092-71a8-abc4-f82d61220f52" xlink:to="loc_us-gaap_StockholdersEquity_019e663d-6092-756c-8c64-e53c007b4333" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonShares_019f8022-a91f-7f77-9839-93152b55a5b8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TreasuryStockCommonShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e663d-6092-71a8-abc4-f82d61220f52" xlink:to="loc_us-gaap_TreasuryStockCommonShares_019f8022-a91f-7f77-9839-93152b55a5b8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_019e663d-6092-7e67-9b98-66b069826d99" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e663d-6092-71a8-abc4-f82d61220f52" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_019e663d-6092-7e67-9b98-66b069826d99" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_019e663d-6092-7c4b-b099-004ab618eeb0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e663d-6092-71a8-abc4-f82d61220f52" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_019e663d-6092-7c4b-b099-004ab618eeb0" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan_019e663d-6092-7cd1-be43-c507de2e9502" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e663d-6092-71a8-abc4-f82d61220f52" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan_019e663d-6092-7cd1-be43-c507de2e9502" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockSharesAcquired_019f6af0-4889-795d-a597-89638fb98dc6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TreasuryStockSharesAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e663d-6092-71a8-abc4-f82d61220f52" xlink:to="loc_us-gaap_TreasuryStockSharesAcquired_019f6af0-4889-795d-a597-89638fb98dc6" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_019f6af0-d535-7cd5-9796-b2a90595bf9b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TreasuryStockValueAcquiredCostMethod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e663d-6092-71a8-abc4-f82d61220f52" xlink:to="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_019f6af0-d535-7cd5-9796-b2a90595bf9b" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019e663d-6092-7968-a57c-26b4e09f4e58" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e663d-6092-71a8-abc4-f82d61220f52" xlink:to="loc_us-gaap_NetIncomeLoss_019e663d-6092-7968-a57c-26b4e09f4e58" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_019e663d-6092-7f87-8308-ae18ccf0521f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e663d-6092-71a8-abc4-f82d61220f52" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_019e663d-6092-7f87-8308-ae18ccf0521f" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesOutstanding_019e663d-6092-7bf5-a5da-827df6273fd8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019e663d-6092-7fec-bfec-8e8fb1ff5fd4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquity"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonShares_019f8024-89a1-7e16-a5dd-a8eee040ff14" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TreasuryStockCommonShares"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.waystar.com/role/SummaryofSignificantAccountingPoliciesRevenueRecognitionDetails" xlink:type="simple" xlink:href="way-20260630.xsd#SummaryofSignificantAccountingPoliciesRevenueRecognitionDetails"/>
  <link:definitionLink xlink:role="http://www.waystar.com/role/SummaryofSignificantAccountingPoliciesRevenueRecognitionDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskLineItems_019e663d-6093-7441-8560-cf74c72440c0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTable_019e663d-6093-7b17-9dbe-9a739e608918" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_019e663d-6093-7441-8560-cf74c72440c0" xlink:to="loc_us-gaap_ConcentrationRiskTable_019e663d-6093-7b17-9dbe-9a739e608918" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019e663d-6093-7ac2-9f27-7ce445ded040" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_019e663d-6093-7b17-9dbe-9a739e608918" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019e663d-6093-7ac2-9f27-7ce445ded040" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019e663d-6093-7ac2-9f27-7ce445ded040_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019e663d-6093-7ac2-9f27-7ce445ded040" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019e663d-6093-7ac2-9f27-7ce445ded040_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019e663d-6093-7bfa-834b-b2a94797065e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019e663d-6093-7ac2-9f27-7ce445ded040" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019e663d-6093-7bfa-834b-b2a94797065e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerMember_019e663d-6093-7047-8b94-bbb78a7a05c4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueFromContractWithCustomerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019e663d-6093-7bfa-834b-b2a94797065e" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerMember_019e663d-6093-7047-8b94-bbb78a7a05c4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_019e663d-6093-78e6-93a0-e4361ef45a51" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_019e663d-6093-7b17-9dbe-9a739e608918" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_019e663d-6093-78e6-93a0-e4361ef45a51" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_019e663d-6093-78e6-93a0-e4361ef45a51_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_019e663d-6093-78e6-93a0-e4361ef45a51" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_019e663d-6093-78e6-93a0-e4361ef45a51_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_019e663d-6093-7b79-b335-315e49427120" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_019e663d-6093-78e6-93a0-e4361ef45a51" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_019e663d-6093-7b79-b335-315e49427120" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProductConcentrationRiskMember_019e663d-6093-7278-aba3-5f9190a56107" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProductConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_019e663d-6093-7b79-b335-315e49427120" xlink:to="loc_us-gaap_ProductConcentrationRiskMember_019e663d-6093-7278-aba3-5f9190a56107" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019e663d-6093-7660-bccc-413202038a21" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_019e663d-6093-7b17-9dbe-9a739e608918" xlink:to="loc_srt_ProductOrServiceAxis_019e663d-6093-7660-bccc-413202038a21" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019e663d-6093-7660-bccc-413202038a21_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_019e663d-6093-7660-bccc-413202038a21" xlink:to="loc_srt_ProductsAndServicesDomain_019e663d-6093-7660-bccc-413202038a21_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019e663d-6093-7309-a148-f126c0697050" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_019e663d-6093-7660-bccc-413202038a21" xlink:to="loc_srt_ProductsAndServicesDomain_019e663d-6093-7309-a148-f126c0697050" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_way_SubscriptionAndVolumeBasedRevenueMember_019e663d-6093-727e-be84-93e16199293b" xlink:href="way-20260630.xsd#way_SubscriptionAndVolumeBasedRevenueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019e663d-6093-7309-a148-f126c0697050" xlink:to="loc_way_SubscriptionAndVolumeBasedRevenueMember_019e663d-6093-727e-be84-93e16199293b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_way_ImplementationFeesAndHardwareSalesMember_019e663d-6093-7a83-a76e-0dc98934812e" xlink:href="way-20260630.xsd#way_ImplementationFeesAndHardwareSalesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019e663d-6093-7309-a148-f126c0697050" xlink:to="loc_way_ImplementationFeesAndHardwareSalesMember_019e663d-6093-7a83-a76e-0dc98934812e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019e663d-6093-7d65-add9-b2351c9a68ec" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_019e663d-6093-7b17-9dbe-9a739e608918" xlink:to="loc_srt_RangeAxis_019e663d-6093-7d65-add9-b2351c9a68ec" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e663d-6093-7d65-add9-b2351c9a68ec_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019e663d-6093-7d65-add9-b2351c9a68ec" xlink:to="loc_srt_RangeMember_019e663d-6093-7d65-add9-b2351c9a68ec_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e663d-6093-78a1-8dc7-f768e6d29b1e" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019e663d-6093-7d65-add9-b2351c9a68ec" xlink:to="loc_srt_RangeMember_019e663d-6093-78a1-8dc7-f768e6d29b1e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019e663d-6093-7ddc-bd6a-793c03842e5a" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019e663d-6093-78a1-8dc7-f768e6d29b1e" xlink:to="loc_srt_MinimumMember_019e663d-6093-7ddc-bd6a-793c03842e5a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019e663d-6093-721c-8e1a-a2f06c24e662" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019e663d-6093-78a1-8dc7-f768e6d29b1e" xlink:to="loc_srt_MaximumMember_019e663d-6093-721c-8e1a-a2f06c24e662" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_019e663d-6093-75b5-81a6-85e258a147fe" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskPercentage1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_019e663d-6093-7441-8560-cf74c72440c0" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_019e663d-6093-75b5-81a6-85e258a147fe" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_way_RevenueContractsTerm_019e663d-6093-70f3-860f-9d2a4c3ba587" xlink:href="way-20260630.xsd#way_RevenueContractsTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_019e663d-6093-7441-8560-cf74c72440c0" xlink:to="loc_way_RevenueContractsTerm_019e663d-6093-70f3-860f-9d2a4c3ba587" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_way_RevenueContractsRenewalTerm_019e663d-6093-7778-9f03-d248cbf2f8a4" xlink:href="way-20260630.xsd#way_RevenueContractsRenewalTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_019e663d-6093-7441-8560-cf74c72440c0" xlink:to="loc_way_RevenueContractsRenewalTerm_019e663d-6093-7778-9f03-d248cbf2f8a4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_way_RevenuePaymentTerm_019e663d-6093-7cea-b42f-fec36080be9f" xlink:href="way-20260630.xsd#way_RevenuePaymentTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_019e663d-6093-7441-8560-cf74c72440c0" xlink:to="loc_way_RevenuePaymentTerm_019e663d-6093-7cea-b42f-fec36080be9f" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.waystar.com/role/SummaryofSignificantAccountingPoliciesContractCostsDetails" xlink:type="simple" xlink:href="way-20260630.xsd#SummaryofSignificantAccountingPoliciesContractCostsDetails"/>
  <link:definitionLink xlink:role="http://www.waystar.com/role/SummaryofSignificantAccountingPoliciesContractCostsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalizedContractCostLineItems_019e663d-6093-7a1b-a981-87d69e7f6f99" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CapitalizedContractCostLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalizedContractCostTable_019e663d-6093-759e-b146-b8ea28e2be46" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CapitalizedContractCostTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_CapitalizedContractCostLineItems_019e663d-6093-7a1b-a981-87d69e7f6f99" xlink:to="loc_us-gaap_CapitalizedContractCostTable_019e663d-6093-759e-b146-b8ea28e2be46" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalizedContractCostAxis_019e663d-6093-7564-a90d-c025de41978d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CapitalizedContractCostAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_CapitalizedContractCostTable_019e663d-6093-759e-b146-b8ea28e2be46" xlink:to="loc_us-gaap_CapitalizedContractCostAxis_019e663d-6093-7564-a90d-c025de41978d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalizedContractCostDomain_019e663d-6093-7564-a90d-c025de41978d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CapitalizedContractCostDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CapitalizedContractCostAxis_019e663d-6093-7564-a90d-c025de41978d" xlink:to="loc_us-gaap_CapitalizedContractCostDomain_019e663d-6093-7564-a90d-c025de41978d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalizedContractCostDomain_019e663d-6093-76d8-9c16-65b943324c4e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CapitalizedContractCostDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CapitalizedContractCostAxis_019e663d-6093-7564-a90d-c025de41978d" xlink:to="loc_us-gaap_CapitalizedContractCostDomain_019e663d-6093-76d8-9c16-65b943324c4e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_way_IncrementalCostsOfObtainingContractMember_019e663d-6093-760a-b622-93b9e2adbf71" xlink:href="way-20260630.xsd#way_IncrementalCostsOfObtainingContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CapitalizedContractCostDomain_019e663d-6093-76d8-9c16-65b943324c4e" xlink:to="loc_way_IncrementalCostsOfObtainingContractMember_019e663d-6093-760a-b622-93b9e2adbf71" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_way_CostsToFulfillContractMember_019e663d-6093-77ea-be3a-e0a62345adbd" xlink:href="way-20260630.xsd#way_CostsToFulfillContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CapitalizedContractCostDomain_019e663d-6093-76d8-9c16-65b943324c4e" xlink:to="loc_way_CostsToFulfillContractMember_019e663d-6093-77ea-be3a-e0a62345adbd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalizedContractCostNet_019e663d-6093-7bdc-a053-a521fa963937" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CapitalizedContractCostNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CapitalizedContractCostLineItems_019e663d-6093-7a1b-a981-87d69e7f6f99" xlink:to="loc_us-gaap_CapitalizedContractCostNet_019e663d-6093-7bdc-a053-a521fa963937" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalizedContractCostAmortization_019e663d-6093-7f44-bf37-6276883ba61b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CapitalizedContractCostAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CapitalizedContractCostLineItems_019e663d-6093-7a1b-a981-87d69e7f6f99" xlink:to="loc_us-gaap_CapitalizedContractCostAmortization_019e663d-6093-7f44-bf37-6276883ba61b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalizedContractCostImpairmentLoss_019e663d-6093-7b98-a9c0-413e233c61df" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CapitalizedContractCostImpairmentLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CapitalizedContractCostLineItems_019e663d-6093-7a1b-a981-87d69e7f6f99" xlink:to="loc_us-gaap_CapitalizedContractCostImpairmentLoss_019e663d-6093-7b98-a9c0-413e233c61df" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.waystar.com/role/RevenueRecognitionDisaggregationofRevenueDetails" xlink:type="simple" xlink:href="way-20260630.xsd#RevenueRecognitionDisaggregationofRevenueDetails"/>
  <link:definitionLink xlink:role="http://www.waystar.com/role/RevenueRecognitionDisaggregationofRevenueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_019e663d-6093-75cd-9595-3119e711c6a9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_019e663d-6093-7692-8f37-f3d0d4b9d1ba" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019e663d-6093-75cd-9595-3119e711c6a9" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_019e663d-6093-7692-8f37-f3d0d4b9d1ba" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019e663d-6093-751f-af3a-ba73cf0e6937" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019e663d-6093-7692-8f37-f3d0d4b9d1ba" xlink:to="loc_srt_ProductOrServiceAxis_019e663d-6093-751f-af3a-ba73cf0e6937" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019e663d-6093-751f-af3a-ba73cf0e6937_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_019e663d-6093-751f-af3a-ba73cf0e6937" xlink:to="loc_srt_ProductsAndServicesDomain_019e663d-6093-751f-af3a-ba73cf0e6937_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019e663d-6093-7fe4-a4c9-170c5f57270e" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_019e663d-6093-751f-af3a-ba73cf0e6937" xlink:to="loc_srt_ProductsAndServicesDomain_019e663d-6093-7fe4-a4c9-170c5f57270e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubscriptionAndCirculationMember_019e663d-6093-7518-a67e-9b55b96d0f9f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubscriptionAndCirculationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019e663d-6093-7fe4-a4c9-170c5f57270e" xlink:to="loc_us-gaap_SubscriptionAndCirculationMember_019e663d-6093-7518-a67e-9b55b96d0f9f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_way_VolumeBasedRevenueMember_019e663d-6093-756b-97b0-b51bd824a763" xlink:href="way-20260630.xsd#way_VolumeBasedRevenueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019e663d-6093-7fe4-a4c9-170c5f57270e" xlink:to="loc_way_VolumeBasedRevenueMember_019e663d-6093-756b-97b0-b51bd824a763" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_way_ImplementationServicesAndOtherRevenueMember_019e663d-6093-7ed4-b814-d06e99505044" xlink:href="way-20260630.xsd#way_ImplementationServicesAndOtherRevenueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019e663d-6093-7fe4-a4c9-170c5f57270e" xlink:to="loc_way_ImplementationServicesAndOtherRevenueMember_019e663d-6093-7ed4-b814-d06e99505044" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HealthCareOrganizationRevenueSourcesAxis_019f6afa-4663-7941-850a-2f92ab81981c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HealthCareOrganizationRevenueSourcesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019e663d-6093-7692-8f37-f3d0d4b9d1ba" xlink:to="loc_us-gaap_HealthCareOrganizationRevenueSourcesAxis_019f6afa-4663-7941-850a-2f92ab81981c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HealthCareOrganizationRevenueSourcesDomain_019f6afa-4663-7941-850a-2f92ab81981c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HealthCareOrganizationRevenueSourcesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HealthCareOrganizationRevenueSourcesAxis_019f6afa-4663-7941-850a-2f92ab81981c" xlink:to="loc_us-gaap_HealthCareOrganizationRevenueSourcesDomain_019f6afa-4663-7941-850a-2f92ab81981c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HealthCareOrganizationRevenueSourcesDomain_019f6afa-76bd-7345-97fd-1bbc62de0c51" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HealthCareOrganizationRevenueSourcesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HealthCareOrganizationRevenueSourcesAxis_019f6afa-4663-7941-850a-2f92ab81981c" xlink:to="loc_us-gaap_HealthCareOrganizationRevenueSourcesDomain_019f6afa-76bd-7345-97fd-1bbc62de0c51" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SelfPayMember_019f6afb-05b7-771c-8f86-248031db7050" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SelfPayMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HealthCareOrganizationRevenueSourcesDomain_019f6afa-76bd-7345-97fd-1bbc62de0c51" xlink:to="loc_us-gaap_SelfPayMember_019f6afb-05b7-771c-8f86-248031db7050" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ThirdPartyPayorMember_019f6afa-c5f5-76f1-bba4-4019551fa891" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ThirdPartyPayorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HealthCareOrganizationRevenueSourcesDomain_019f6afa-76bd-7345-97fd-1bbc62de0c51" xlink:to="loc_us-gaap_ThirdPartyPayorMember_019f6afa-c5f5-76f1-bba4-4019551fa891" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019e663d-6093-7312-9463-c53180b7222d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019e663d-6093-75cd-9595-3119e711c6a9" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019e663d-6093-7312-9463-c53180b7222d" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.waystar.com/role/RevenueRecognitionTransactionPriceAllocatedtoRemainingPerformanceObligationsDetails" xlink:type="simple" xlink:href="way-20260630.xsd#RevenueRecognitionTransactionPriceAllocatedtoRemainingPerformanceObligationsDetails"/>
  <link:definitionLink xlink:role="http://www.waystar.com/role/RevenueRecognitionTransactionPriceAllocatedtoRemainingPerformanceObligationsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_019e663d-6093-7327-bf6a-40e015149858" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_019e663d-6093-7e21-be16-2e70034aabb3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_019e663d-6093-7327-bf6a-40e015149858" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_019e663d-6093-7e21-be16-2e70034aabb3" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_019e663d-6093-7647-b3d7-8f2c9db60a8b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_019e663d-6093-7e21-be16-2e70034aabb3" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_019e663d-6093-7647-b3d7-8f2c9db60a8b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_019e663d-6093-7c8b-bd33-4d75d562d525" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_019e663d-6093-7327-bf6a-40e015149858" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_019e663d-6093-7c8b-bd33-4d75d562d525" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligation_019e663d-6093-74b2-8ab4-1d0d9799072c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueRemainingPerformanceObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_019e663d-6093-7327-bf6a-40e015149858" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligation_019e663d-6093-74b2-8ab4-1d0d9799072c" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.waystar.com/role/RevenueRecognitionTransactionPriceAllocatedtoRemainingPerformanceObligationsDetails_1" xlink:type="simple" xlink:href="way-20260630.xsd#RevenueRecognitionTransactionPriceAllocatedtoRemainingPerformanceObligationsDetails_1"/>
  <link:definitionLink xlink:role="http://www.waystar.com/role/RevenueRecognitionTransactionPriceAllocatedtoRemainingPerformanceObligationsDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_019e663d-6093-7327-bf6a-40e015149858" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_019e663d-6093-7e21-be16-2e70034aabb3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_019e663d-6093-7327-bf6a-40e015149858" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_019e663d-6093-7e21-be16-2e70034aabb3" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_019e663d-6093-7c8b-bd33-4d75d562d525" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_019e663d-6093-7327-bf6a-40e015149858" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_019e663d-6093-7c8b-bd33-4d75d562d525" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligation_019e663d-6093-74b2-8ab4-1d0d9799072c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueRemainingPerformanceObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_019e663d-6093-7327-bf6a-40e015149858" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligation_019e663d-6093-74b2-8ab4-1d0d9799072c" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.waystar.com/role/SegmentsReconciliationofRevenuetoConsolidatedNetIncomeDetails" xlink:type="simple" xlink:href="way-20260630.xsd#SegmentsReconciliationofRevenuetoConsolidatedNetIncomeDetails"/>
  <link:definitionLink xlink:role="http://www.waystar.com/role/SegmentsReconciliationofRevenuetoConsolidatedNetIncomeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_019e663d-6093-7fd4-a01e-838e3c285a97" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019e663d-6093-7e4e-9e22-4275d129feb7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e663d-6093-7fd4-a01e-838e3c285a97" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019e663d-6093-7e4e-9e22-4275d129feb7" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019e663d-6093-7589-b626-bf17fc29cbad" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019e663d-6093-7e4e-9e22-4275d129feb7" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019e663d-6093-7589-b626-bf17fc29cbad" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e663d-6093-7589-b626-bf17fc29cbad_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e663d-6093-7589-b626-bf17fc29cbad" xlink:to="loc_us-gaap_SegmentDomain_019e663d-6093-7589-b626-bf17fc29cbad_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e663d-6093-76bd-927f-bddfdf46169b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e663d-6093-7589-b626-bf17fc29cbad" xlink:to="loc_us-gaap_SegmentDomain_019e663d-6093-76bd-927f-bddfdf46169b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_way_ReportableSegmentMember_019e663d-6093-7c1f-8090-3d51047bdb28" xlink:href="way-20260630.xsd#way_ReportableSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019e663d-6093-76bd-927f-bddfdf46169b" xlink:to="loc_way_ReportableSegmentMember_019e663d-6093-7c1f-8090-3d51047bdb28" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019e663d-6093-712b-aa8c-8fb5b7eb6516" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e663d-6093-7fd4-a01e-838e3c285a97" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019e663d-6093-712b-aa8c-8fb5b7eb6516" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_way_ExpensesAbstract_019e663d-6093-7abc-aa5b-5ef8a6b4f6de" xlink:href="way-20260630.xsd#way_ExpensesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e663d-6093-7fd4-a01e-838e3c285a97" xlink:to="loc_way_ExpensesAbstract_019e663d-6093-7abc-aa5b-5ef8a6b4f6de" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_way_MaterialsAndConnectivity_019e663d-6093-7970-81c4-03e64832deb4" xlink:href="way-20260630.xsd#way_MaterialsAndConnectivity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_way_ExpensesAbstract_019e663d-6093-7abc-aa5b-5ef8a6b4f6de" xlink:to="loc_way_MaterialsAndConnectivity_019e663d-6093-7970-81c4-03e64832deb4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LaborAndRelatedExpense_019e663d-6093-7f7d-bc54-b1dc090fed6c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LaborAndRelatedExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_way_ExpensesAbstract_019e663d-6093-7abc-aa5b-5ef8a6b4f6de" xlink:to="loc_us-gaap_LaborAndRelatedExpense_019e663d-6093-7f7d-bc54-b1dc090fed6c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpense_019e663d-6093-7bf5-b112-b5488c2e7de2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ResearchAndDevelopmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_way_ExpensesAbstract_019e663d-6093-7abc-aa5b-5ef8a6b4f6de" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpense_019e663d-6093-7bf5-b112-b5488c2e7de2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingAndMarketingExpense_019e663d-6093-716b-a470-2e810eb2e974" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SellingAndMarketingExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_way_ExpensesAbstract_019e663d-6093-7abc-aa5b-5ef8a6b4f6de" xlink:to="loc_us-gaap_SellingAndMarketingExpense_019e663d-6093-716b-a470-2e810eb2e974" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpense_019e663d-6093-7927-8dea-c16468048745" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_way_ExpensesAbstract_019e663d-6093-7abc-aa5b-5ef8a6b4f6de" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpense_019e663d-6093-7927-8dea-c16468048745" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Depreciation_019e663d-6093-7e3a-ae96-b87bb825c600" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Depreciation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_way_ExpensesAbstract_019e663d-6093-7abc-aa5b-5ef8a6b4f6de" xlink:to="loc_us-gaap_Depreciation_019e663d-6093-7e3a-ae96-b87bb825c600" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentForAmortization_019e663d-6093-7894-b900-2ef0eb344b01" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdjustmentForAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_way_ExpensesAbstract_019e663d-6093-7abc-aa5b-5ef8a6b4f6de" xlink:to="loc_us-gaap_AdjustmentForAmortization_019e663d-6093-7894-b900-2ef0eb344b01" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonoperatingIncomeExpense_019e663d-6093-74dc-ac4e-0050e8d1c3dc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_way_ExpensesAbstract_019e663d-6093-7abc-aa5b-5ef8a6b4f6de" xlink:to="loc_us-gaap_NonoperatingIncomeExpense_019e663d-6093-74dc-ac4e-0050e8d1c3dc" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_019e663d-6093-7bbb-ae1c-839c4861e95b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_way_ExpensesAbstract_019e663d-6093-7abc-aa5b-5ef8a6b4f6de" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_019e663d-6093-7bbb-ae1c-839c4861e95b" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019e663d-6093-7e00-9c62-1fafdfd45238" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e663d-6093-7fd4-a01e-838e3c285a97" xlink:to="loc_us-gaap_NetIncomeLoss_019e663d-6093-7e00-9c62-1fafdfd45238" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.waystar.com/role/InvestmentsSecuritiesDetails" xlink:type="simple" xlink:href="way-20260630.xsd#InvestmentsSecuritiesDetails"/>
  <link:definitionLink xlink:role="http://www.waystar.com/role/InvestmentsSecuritiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e663d-6093-7acb-977f-6b333907ae44" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_019e663d-6093-7ea0-9700-83aa493ec0e1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e663d-6093-7acb-977f-6b333907ae44" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_019e663d-6093-7ea0-9700-83aa493ec0e1" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_019e663d-6093-7fd3-a3a9-acaca9ef2b20" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_019e663d-6093-7ea0-9700-83aa493ec0e1" xlink:to="loc_us-gaap_FinancialInstrumentAxis_019e663d-6093-7fd3-a3a9-acaca9ef2b20" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e663d-6093-7fd3-a3a9-acaca9ef2b20_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e663d-6093-7fd3-a3a9-acaca9ef2b20" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e663d-6093-7fd3-a3a9-acaca9ef2b20_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e663d-6093-700c-a718-be1d918885f6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e663d-6093-7fd3-a3a9-acaca9ef2b20" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e663d-6093-700c-a718-be1d918885f6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialPaperMember_019e663d-6093-7cc4-920a-859810f30fec" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommercialPaperMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e663d-6093-700c-a718-be1d918885f6" xlink:to="loc_us-gaap_CommercialPaperMember_019e663d-6093-7cc4-920a-859810f30fec" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateNoteSecuritiesMember_019e663d-6093-71d6-9969-dcdb7f610f05" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CorporateNoteSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e663d-6093-700c-a718-be1d918885f6" xlink:to="loc_us-gaap_CorporateNoteSecuritiesMember_019e663d-6093-71d6-9969-dcdb7f610f05" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USTreasuryBillSecuritiesMember_019e663d-6093-78ca-b19b-cbc4fc6a74db" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_USTreasuryBillSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e663d-6093-700c-a718-be1d918885f6" xlink:to="loc_us-gaap_USTreasuryBillSecuritiesMember_019e663d-6093-78ca-b19b-cbc4fc6a74db" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_019e663d-6093-7e10-9e0b-dbcb1c148ac8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_USGovernmentAgenciesDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e663d-6093-700c-a718-be1d918885f6" xlink:to="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_019e663d-6093-7e10-9e0b-dbcb1c148ac8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostCurrent_019e663d-6093-7d94-939d-12e578431816" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e663d-6093-7acb-977f-6b333907ae44" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostCurrent_019e663d-6093-7d94-939d-12e578431816" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleAllowanceForCreditLossCurrent_019e663d-6093-77de-a9ea-def3df4f79ce" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleAllowanceForCreditLossCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e663d-6093-7acb-977f-6b333907ae44" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleAllowanceForCreditLossCurrent_019e663d-6093-77de-a9ea-def3df4f79ce" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_019e663d-6093-7f80-bce6-03a4a4e80a41" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e663d-6093-7acb-977f-6b333907ae44" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_019e663d-6093-7f80-bce6-03a4a4e80a41" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_019e663d-6093-71c1-ae36-cc210b4d9b58" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e663d-6093-7acb-977f-6b333907ae44" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_019e663d-6093-71c1-ae36-cc210b4d9b58" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecuritiesCurrent_019e663d-6093-798d-8e76-128cf7d89ce1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecuritiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019e663d-6093-7acb-977f-6b333907ae44" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecuritiesCurrent_019e663d-6093-798d-8e76-128cf7d89ce1" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.waystar.com/role/FairValueMeasurementsandDisclosuresFairValueHierarchyforFinancialAssetsandLiabilitiesMeasuredatFairValueDetails" xlink:type="simple" xlink:href="way-20260630.xsd#FairValueMeasurementsandDisclosuresFairValueHierarchyforFinancialAssetsandLiabilitiesMeasuredatFairValueDetails"/>
  <link:definitionLink xlink:role="http://www.waystar.com/role/FairValueMeasurementsandDisclosuresFairValueHierarchyforFinancialAssetsandLiabilitiesMeasuredatFairValueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_019e663d-6093-7cbd-acb6-b09337c740e6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByBalanceSheetGroupingTable_019e663d-6093-7736-b1f8-8717ff26309f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByBalanceSheetGroupingTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_019e663d-6093-7cbd-acb6-b09337c740e6" xlink:to="loc_us-gaap_FairValueByBalanceSheetGroupingTable_019e663d-6093-7736-b1f8-8717ff26309f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementBasisAxis_019e663d-6093-701d-a0e7-f5905e9033ae" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByMeasurementBasisAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingTable_019e663d-6093-7736-b1f8-8717ff26309f" xlink:to="loc_us-gaap_FairValueByMeasurementBasisAxis_019e663d-6093-701d-a0e7-f5905e9033ae" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019e663d-6093-701d-a0e7-f5905e9033ae_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_019e663d-6093-701d-a0e7-f5905e9033ae" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019e663d-6093-701d-a0e7-f5905e9033ae_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueDisclosureItemAmountsDomain_019e663d-6093-7196-bd5a-5e4231b0fdd7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueDisclosureItemAmountsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_019e663d-6093-701d-a0e7-f5905e9033ae" xlink:to="loc_us-gaap_FairValueDisclosureItemAmountsDomain_019e663d-6093-7196-bd5a-5e4231b0fdd7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019e663d-6093-7b96-a29e-d5f82626d7c8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_019e663d-6093-7196-bd5a-5e4231b0fdd7" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019e663d-6093-7b96-a29e-d5f82626d7c8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_019e663d-6093-7a8d-82af-c3376a102037" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CarryingReportedAmountFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019e663d-6093-7b96-a29e-d5f82626d7c8" xlink:to="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_019e663d-6093-7a8d-82af-c3376a102037" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_019e663d-6093-7336-95c6-9654a58b5de1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EstimateOfFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019e663d-6093-7b96-a29e-d5f82626d7c8" xlink:to="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_019e663d-6093-7336-95c6-9654a58b5de1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e663d-6093-7589-9220-547046e71cb8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingTable_019e663d-6093-7736-b1f8-8717ff26309f" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e663d-6093-7589-9220-547046e71cb8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e663d-6093-7589-9220-547046e71cb8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e663d-6093-7589-9220-547046e71cb8" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e663d-6093-7589-9220-547046e71cb8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e663d-6093-7319-8aa9-32e9ae16cd50" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e663d-6093-7589-9220-547046e71cb8" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e663d-6093-7319-8aa9-32e9ae16cd50" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_019e663d-6093-7151-bee6-adb64a8f5927" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e663d-6093-7319-8aa9-32e9ae16cd50" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_019e663d-6093-7151-bee6-adb64a8f5927" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_019e663d-6093-7437-a995-c560de56a80a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e663d-6093-7319-8aa9-32e9ae16cd50" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_019e663d-6093-7437-a995-c560de56a80a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_019e663d-6093-78b3-9459-6ac121df8580" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e663d-6093-7319-8aa9-32e9ae16cd50" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_019e663d-6093-78b3-9459-6ac121df8580" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_019e663d-6093-77b5-a8e2-7c5c3812adb2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingTable_019e663d-6093-7736-b1f8-8717ff26309f" xlink:to="loc_us-gaap_FinancialInstrumentAxis_019e663d-6093-77b5-a8e2-7c5c3812adb2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e663d-6093-77b5-a8e2-7c5c3812adb2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e663d-6093-77b5-a8e2-7c5c3812adb2" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e663d-6093-77b5-a8e2-7c5c3812adb2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e663d-6093-7115-9e1b-4d51814e0a69" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e663d-6093-77b5-a8e2-7c5c3812adb2" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e663d-6093-7115-9e1b-4d51814e0a69" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialPaperMember_019e663d-6093-7888-bef3-15330f23b087" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommercialPaperMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e663d-6093-7115-9e1b-4d51814e0a69" xlink:to="loc_us-gaap_CommercialPaperMember_019e663d-6093-7888-bef3-15330f23b087" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateNoteSecuritiesMember_019e663d-6093-7f6f-9451-1d8d3796744a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CorporateNoteSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e663d-6093-7115-9e1b-4d51814e0a69" xlink:to="loc_us-gaap_CorporateNoteSecuritiesMember_019e663d-6093-7f6f-9451-1d8d3796744a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USTreasuryBillSecuritiesMember_019e663d-6093-735d-a9a0-888c3cf5009c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_USTreasuryBillSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e663d-6093-7115-9e1b-4d51814e0a69" xlink:to="loc_us-gaap_USTreasuryBillSecuritiesMember_019e663d-6093-735d-a9a0-888c3cf5009c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_019e663d-6093-7331-80f3-b235bdc95939" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_USGovernmentAgenciesDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e663d-6093-7115-9e1b-4d51814e0a69" xlink:to="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_019e663d-6093-7331-80f3-b235bdc95939" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAxis_019e663d-6093-7160-8d87-c0dd4c4b07a4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashAndCashEquivalentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingTable_019e663d-6093-7736-b1f8-8717ff26309f" xlink:to="loc_us-gaap_CashAndCashEquivalentsAxis_019e663d-6093-7160-8d87-c0dd4c4b07a4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_019e663d-6093-7160-8d87-c0dd4c4b07a4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CashAndCashEquivalentsAxis_019e663d-6093-7160-8d87-c0dd4c4b07a4" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_019e663d-6093-7160-8d87-c0dd4c4b07a4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_019e663d-6093-7588-aa11-9aabb2e2a528" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CashAndCashEquivalentsAxis_019e663d-6093-7160-8d87-c0dd4c4b07a4" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_019e663d-6093-7588-aa11-9aabb2e2a528" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MoneyMarketFundsMember_019e663d-6093-71b1-8283-97eb1d4dfbb3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MoneyMarketFundsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_019e663d-6093-7588-aa11-9aabb2e2a528" xlink:to="loc_us-gaap_MoneyMarketFundsMember_019e663d-6093-71b1-8283-97eb1d4dfbb3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019e663d-6093-7429-a31b-268977406578" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingTable_019e663d-6093-7736-b1f8-8717ff26309f" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019e663d-6093-7429-a31b-268977406578" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e663d-6093-7429-a31b-268977406578_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e663d-6093-7429-a31b-268977406578" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e663d-6093-7429-a31b-268977406578_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e663d-6093-7c46-b255-fd7f079fcfa2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e663d-6093-7429-a31b-268977406578" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e663d-6093-7c46-b255-fd7f079fcfa2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_019e663d-6093-7566-91ef-40443765cc46" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e663d-6093-7c46-b255-fd7f079fcfa2" xlink:to="loc_us-gaap_InterestRateSwapMember_019e663d-6093-7566-91ef-40443765cc46" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateCapMember_019e663d-6093-778b-b294-7d90d319581b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestRateCapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e663d-6093-7c46-b255-fd7f079fcfa2" xlink:to="loc_us-gaap_InterestRateCapMember_019e663d-6093-778b-b294-7d90d319581b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecuritiesCurrent_019e663d-6093-7707-ae3e-1ce386de331a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecuritiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_019e663d-6093-7cbd-acb6-b09337c740e6" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecuritiesCurrent_019e663d-6093-7707-ae3e-1ce386de331a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_019e663d-6093-77b6-be31-bf926a6b2a22" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashAndCashEquivalentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_019e663d-6093-7cbd-acb6-b09337c740e6" xlink:to="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_019e663d-6093-77b6-be31-bf926a6b2a22" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetsCurrent_019e663d-6093-7a6d-a8bf-eef2f838ebe1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_019e663d-6093-7cbd-acb6-b09337c740e6" xlink:to="loc_us-gaap_DerivativeAssetsCurrent_019e663d-6093-7a6d-a8bf-eef2f838ebe1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilitiesCurrent_019e663d-6093-7b17-8fe9-63ed795b9a92" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_019e663d-6093-7cbd-acb6-b09337c740e6" xlink:to="loc_us-gaap_DerivativeLiabilitiesCurrent_019e663d-6093-7b17-8fe9-63ed795b9a92" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilitiesNoncurrent_019e663d-6093-7b62-8674-d300750bcf78" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilitiesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_019e663d-6093-7cbd-acb6-b09337c740e6" xlink:to="loc_us-gaap_DerivativeLiabilitiesNoncurrent_019e663d-6093-7b62-8674-d300750bcf78" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.waystar.com/role/FairValueMeasurementsandDisclosuresAdditionalInformationDetails" xlink:type="simple" xlink:href="way-20260630.xsd#FairValueMeasurementsandDisclosuresAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://www.waystar.com/role/FairValueMeasurementsandDisclosuresAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_019e663d-6093-71b8-a0ee-d73054956cc8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByBalanceSheetGroupingTable_019e663d-6093-74ce-a334-e0b2e080d754" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByBalanceSheetGroupingTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_019e663d-6093-71b8-a0ee-d73054956cc8" xlink:to="loc_us-gaap_FairValueByBalanceSheetGroupingTable_019e663d-6093-74ce-a334-e0b2e080d754" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019e663d-6093-713b-87ff-7e06fa370661" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingTable_019e663d-6093-74ce-a334-e0b2e080d754" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019e663d-6093-713b-87ff-7e06fa370661" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019e663d-6093-713b-87ff-7e06fa370661_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019e663d-6093-713b-87ff-7e06fa370661" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019e663d-6093-713b-87ff-7e06fa370661_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019e663d-6093-76d3-b6e1-39413c494293" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019e663d-6093-713b-87ff-7e06fa370661" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019e663d-6093-76d3-b6e1-39413c494293" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_019e663d-6093-7201-a75b-1fe602c62ee2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019e663d-6093-76d3-b6e1-39413c494293" xlink:to="loc_us-gaap_LineOfCreditMember_019e663d-6093-7201-a75b-1fe602c62ee2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_019e663d-6093-71bc-8161-c9629d67deac" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingTable_019e663d-6093-74ce-a334-e0b2e080d754" xlink:to="loc_us-gaap_CreditFacilityAxis_019e663d-6093-71bc-8161-c9629d67deac" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019e663d-6093-71bc-8161-c9629d67deac_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_019e663d-6093-71bc-8161-c9629d67deac" xlink:to="loc_us-gaap_CreditFacilityDomain_019e663d-6093-71bc-8161-c9629d67deac_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019e663d-6093-701d-9f47-22221a517e4d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_019e663d-6093-71bc-8161-c9629d67deac" xlink:to="loc_us-gaap_CreditFacilityDomain_019e663d-6093-701d-9f47-22221a517e4d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_way_FirstLienCreditFacilityMember_019e663d-6093-710f-8726-10175993e04a" xlink:href="way-20260630.xsd#way_FirstLienCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019e663d-6093-701d-9f47-22221a517e4d" xlink:to="loc_way_FirstLienCreditFacilityMember_019e663d-6093-710f-8726-10175993e04a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementBasisAxis_019e663d-6093-782f-9864-b341d8dd3d77" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByMeasurementBasisAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingTable_019e663d-6093-74ce-a334-e0b2e080d754" xlink:to="loc_us-gaap_FairValueByMeasurementBasisAxis_019e663d-6093-782f-9864-b341d8dd3d77" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019e663d-6093-782f-9864-b341d8dd3d77_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_019e663d-6093-782f-9864-b341d8dd3d77" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019e663d-6093-782f-9864-b341d8dd3d77_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueDisclosureItemAmountsDomain_019e663d-6093-7e6f-954b-e83ef2ea2505" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueDisclosureItemAmountsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_019e663d-6093-782f-9864-b341d8dd3d77" xlink:to="loc_us-gaap_FairValueDisclosureItemAmountsDomain_019e663d-6093-7e6f-954b-e83ef2ea2505" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019e663d-6093-74b2-9d3a-4e80c5295d7d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_019e663d-6093-7e6f-954b-e83ef2ea2505" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019e663d-6093-74b2-9d3a-4e80c5295d7d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_019e663d-6093-7d2f-8fcf-d9cc81e60951" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CarryingReportedAmountFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019e663d-6093-74b2-9d3a-4e80c5295d7d" xlink:to="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_019e663d-6093-7d2f-8fcf-d9cc81e60951" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_019e663d-6093-71bd-b66a-8218eb504af7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EstimateOfFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019e663d-6093-74b2-9d3a-4e80c5295d7d" xlink:to="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_019e663d-6093-71bd-b66a-8218eb504af7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtFairValue_019e663d-6093-7bf4-bafc-b8ef23d90192" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebtFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_019e663d-6093-71b8-a0ee-d73054956cc8" xlink:to="loc_us-gaap_LongTermDebtFairValue_019e663d-6093-7bf4-bafc-b8ef23d90192" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityTransfersNet_019e663d-6093-74ce-860b-3d6edeffe517" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityTransfersNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_019e663d-6093-71b8-a0ee-d73054956cc8" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityTransfersNet_019e663d-6093-74ce-860b-3d6edeffe517" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.waystar.com/role/PropertyandEquipmentNetBalanceofMajorClassesofPropertyandEquipmentDetails" xlink:type="simple" xlink:href="way-20260630.xsd#PropertyandEquipmentNetBalanceofMajorClassesofPropertyandEquipmentDetails"/>
  <link:definitionLink xlink:role="http://www.waystar.com/role/PropertyandEquipmentNetBalanceofMajorClassesofPropertyandEquipmentDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019e663d-6093-723a-9cf9-776fec3dabdd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019e663d-6093-790e-9160-571cc3461029" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019e663d-6093-723a-9cf9-776fec3dabdd" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019e663d-6093-790e-9160-571cc3461029" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019e663d-6093-7bd1-a3b0-107848fa7786" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019e663d-6093-790e-9160-571cc3461029" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019e663d-6093-7bd1-a3b0-107848fa7786" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e663d-6093-7bd1-a3b0-107848fa7786_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019e663d-6093-7bd1-a3b0-107848fa7786" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e663d-6093-7bd1-a3b0-107848fa7786_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e663d-6093-743a-abbd-a9f47030f8db" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019e663d-6093-7bd1-a3b0-107848fa7786" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e663d-6093-743a-abbd-a9f47030f8db" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComputerEquipmentMember_019e663d-6093-7465-9f11-ed00b6f955a2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ComputerEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e663d-6093-743a-abbd-a9f47030f8db" xlink:to="loc_us-gaap_ComputerEquipmentMember_019e663d-6093-7465-9f11-ed00b6f955a2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SoftwareDevelopmentMember_019f717f-65d1-7a51-9443-22f2a78af394" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SoftwareDevelopmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e663d-6093-743a-abbd-a9f47030f8db" xlink:to="loc_us-gaap_SoftwareDevelopmentMember_019f717f-65d1-7a51-9443-22f2a78af394" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SoftwarePurchasedMember_019f717f-3a35-770e-8184-a7cc78d446bd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SoftwarePurchasedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e663d-6093-743a-abbd-a9f47030f8db" xlink:to="loc_us-gaap_SoftwarePurchasedMember_019f717f-3a35-770e-8184-a7cc78d446bd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FurnitureAndFixturesMember_019e663d-6093-774b-9041-28a0c834d1a8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FurnitureAndFixturesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e663d-6093-743a-abbd-a9f47030f8db" xlink:to="loc_us-gaap_FurnitureAndFixturesMember_019e663d-6093-774b-9041-28a0c834d1a8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OfficeEquipmentMember_019e663d-6093-7d1c-aac0-4d6f4a0025a3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OfficeEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e663d-6093-743a-abbd-a9f47030f8db" xlink:to="loc_us-gaap_OfficeEquipmentMember_019e663d-6093-7d1c-aac0-4d6f4a0025a3" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseholdImprovementsMember_019e663d-6093-7fa3-a18c-64bac2979a4a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LeaseholdImprovementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e663d-6093-743a-abbd-a9f47030f8db" xlink:to="loc_us-gaap_LeaseholdImprovementsMember_019e663d-6093-7fa3-a18c-64bac2979a4a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SoftwareInDevelopmentMember_019f717b-4020-7b59-927f-5bb561bfffe1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SoftwareInDevelopmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e663d-6093-743a-abbd-a9f47030f8db" xlink:to="loc_us-gaap_SoftwareInDevelopmentMember_019f717b-4020-7b59-927f-5bb561bfffe1" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization_019e663d-6093-73ff-8a90-30c34faed20d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019e663d-6093-723a-9cf9-776fec3dabdd" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization_019e663d-6093-73ff-8a90-30c34faed20d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization_019e663d-6093-7459-bfc1-8a13057c4db7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019e663d-6093-723a-9cf9-776fec3dabdd" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization_019e663d-6093-7459-bfc1-8a13057c4db7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_019e663d-6093-76b8-8cb1-6c4328aa25e2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019e663d-6093-723a-9cf9-776fec3dabdd" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_019e663d-6093-76b8-8cb1-6c4328aa25e2" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.waystar.com/role/PropertyandEquipmentNetAdditionalInformationDetails" xlink:type="simple" xlink:href="way-20260630.xsd#PropertyandEquipmentNetAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://www.waystar.com/role/PropertyandEquipmentNetAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019f7180-c952-7010-8c72-cd330604df63" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019f717e-431d-7f35-b043-2f9e49b5abc5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019f7180-c952-7010-8c72-cd330604df63" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019f717e-431d-7f35-b043-2f9e49b5abc5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019f717e-7931-7346-9dc8-5f3b0de1f8a0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019f717e-431d-7f35-b043-2f9e49b5abc5" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019f717e-7931-7346-9dc8-5f3b0de1f8a0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019f717e-7931-7346-9dc8-5f3b0de1f8a0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019f717e-7931-7346-9dc8-5f3b0de1f8a0" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019f717e-7931-7346-9dc8-5f3b0de1f8a0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019f717e-a1f5-71dc-a369-611d60a334bb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019f717e-7931-7346-9dc8-5f3b0de1f8a0" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019f717e-a1f5-71dc-a369-611d60a334bb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember_019f717e-e908-791d-ada4-2fd03abbb279" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SoftwareAndSoftwareDevelopmentCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019f717e-a1f5-71dc-a369-611d60a334bb" xlink:to="loc_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember_019f717e-e908-791d-ada4-2fd03abbb279" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Depreciation_019f7181-b187-7097-aff9-195e8824c778" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Depreciation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019f7180-c952-7010-8c72-cd330604df63" xlink:to="loc_us-gaap_Depreciation_019f7181-b187-7097-aff9-195e8824c778" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAdditions_019f7180-c952-730f-8ef6-c3213a79ac1f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentAdditions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019f7180-c952-7010-8c72-cd330604df63" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAdditions_019f7180-c952-730f-8ef6-c3213a79ac1f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_019f7182-c53e-7935-9487-58298dcf239b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019f7180-c952-7010-8c72-cd330604df63" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_019f7182-c53e-7935-9487-58298dcf239b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairmentOfLongLivedAssetsHeldForUse_019ede88-c03e-7793-80c3-0068aa090969" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ImpairmentOfLongLivedAssetsHeldForUse"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019f7180-c952-7010-8c72-cd330604df63" xlink:to="loc_us-gaap_ImpairmentOfLongLivedAssetsHeldForUse_019ede88-c03e-7793-80c3-0068aa090969" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.waystar.com/role/GoodwillandOtherIntangibleAssetsAmortizationforDefinitelivedIntangibleAssetsDetails" xlink:type="simple" xlink:href="way-20260630.xsd#GoodwillandOtherIntangibleAssetsAmortizationforDefinitelivedIntangibleAssetsDetails"/>
  <link:definitionLink xlink:role="http://www.waystar.com/role/GoodwillandOtherIntangibleAssetsAmortizationforDefinitelivedIntangibleAssetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_019e663d-6093-736e-bfd8-7e4c72af6245" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_019e663d-6093-7b23-91b9-909a6c39cb83" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_019e663d-6093-736e-bfd8-7e4c72af6245" xlink:to="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_019e663d-6093-7b23-91b9-909a6c39cb83" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019e663d-6093-77e1-ba4f-c04d5a3ead11" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_019e663d-6093-7b23-91b9-909a6c39cb83" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019e663d-6093-77e1-ba4f-c04d5a3ead11" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e663d-6093-77e1-ba4f-c04d5a3ead11_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019e663d-6093-77e1-ba4f-c04d5a3ead11" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e663d-6093-77e1-ba4f-c04d5a3ead11_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e663d-6093-7797-a9cb-91334b9c0c10" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019e663d-6093-77e1-ba4f-c04d5a3ead11" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e663d-6093-7797-a9cb-91334b9c0c10" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_019e663d-6093-711f-892d-d6a65d1ffb35" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e663d-6093-7797-a9cb-91334b9c0c10" xlink:to="loc_us-gaap_CustomerRelationshipsMember_019e663d-6093-711f-892d-d6a65d1ffb35" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TechnologyBasedIntangibleAssetsMember_019f71b4-19a2-75df-8741-d16abb5733a2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TechnologyBasedIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e663d-6093-7797-a9cb-91334b9c0c10" xlink:to="loc_us-gaap_TechnologyBasedIntangibleAssetsMember_019f71b4-19a2-75df-8741-d16abb5733a2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TrademarksAndTradeNamesMember_019e663d-6093-7443-bbe5-a98a75007c6b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TrademarksAndTradeNamesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e663d-6093-7797-a9cb-91334b9c0c10" xlink:to="loc_us-gaap_TrademarksAndTradeNamesMember_019e663d-6093-7443-bbe5-a98a75007c6b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_019e663d-6093-7970-85ed-7b7ace63ca43" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_019e663d-6093-736e-bfd8-7e4c72af6245" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_019e663d-6093-7970-85ed-7b7ace63ca43" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_019e663d-6093-7108-86a0-1a9410d5dbad" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_019e663d-6093-736e-bfd8-7e4c72af6245" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_019e663d-6093-7108-86a0-1a9410d5dbad" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_019e663d-6093-7430-bf23-ebd2df1d944f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_019e663d-6093-736e-bfd8-7e4c72af6245" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNet_019e663d-6093-7430-bf23-ebd2df1d944f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsRemainingAmortizationPeriod1_019e663d-6093-709d-865c-3fa08d9f401d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsRemainingAmortizationPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_019e663d-6093-736e-bfd8-7e4c72af6245" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsRemainingAmortizationPeriod1_019e663d-6093-709d-865c-3fa08d9f401d" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.waystar.com/role/AccountsReceivableSecuritizationDetails" xlink:type="simple" xlink:href="way-20260630.xsd#AccountsReceivableSecuritizationDetails"/>
  <link:definitionLink xlink:role="http://www.waystar.com/role/AccountsReceivableSecuritizationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019e663d-6093-76fe-8e2e-37e6d6947f65" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_019e663d-6093-7811-9b8d-23754c4ff4d7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e663d-6093-76fe-8e2e-37e6d6947f65" xlink:to="loc_us-gaap_DebtInstrumentTable_019e663d-6093-7811-9b8d-23754c4ff4d7" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019e663d-6093-74b6-9bf4-8bb7f9831a28" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019e663d-6093-7811-9b8d-23754c4ff4d7" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019e663d-6093-74b6-9bf4-8bb7f9831a28" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019e663d-6093-74b6-9bf4-8bb7f9831a28_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019e663d-6093-74b6-9bf4-8bb7f9831a28" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019e663d-6093-74b6-9bf4-8bb7f9831a28_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019e663d-6093-766e-be71-46b8419d0942" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019e663d-6093-74b6-9bf4-8bb7f9831a28" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019e663d-6093-766e-be71-46b8419d0942" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_019e663d-6093-784e-876b-29cb50e0aca2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019e663d-6093-766e-be71-46b8419d0942" xlink:to="loc_us-gaap_LineOfCreditMember_019e663d-6093-784e-876b-29cb50e0aca2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_019e663d-6093-7745-86ab-8c1b55e2faf9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019e663d-6093-7811-9b8d-23754c4ff4d7" xlink:to="loc_us-gaap_CreditFacilityAxis_019e663d-6093-7745-86ab-8c1b55e2faf9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019e663d-6093-7745-86ab-8c1b55e2faf9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_019e663d-6093-7745-86ab-8c1b55e2faf9" xlink:to="loc_us-gaap_CreditFacilityDomain_019e663d-6093-7745-86ab-8c1b55e2faf9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019e663d-6093-771e-bca7-046733722b5b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_019e663d-6093-7745-86ab-8c1b55e2faf9" xlink:to="loc_us-gaap_CreditFacilityDomain_019e663d-6093-771e-bca7-046733722b5b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_way_ReceivablesFacilityMember_019e663d-6093-7cf6-941b-8da210e09fe9" xlink:href="way-20260630.xsd#way_ReceivablesFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019e663d-6093-771e-bca7-046733722b5b" xlink:to="loc_way_ReceivablesFacilityMember_019e663d-6093-7cf6-941b-8da210e09fe9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_019e663d-6093-7c5b-8565-5453c53af505" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e663d-6093-76fe-8e2e-37e6d6947f65" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_019e663d-6093-7c5b-8565-5453c53af505" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTerm_019e663d-6093-71a7-a733-b7fa43e8bcb5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e663d-6093-76fe-8e2e-37e6d6947f65" xlink:to="loc_us-gaap_DebtInstrumentTerm_019e663d-6093-71a7-a733-b7fa43e8bcb5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019e663d-6093-762b-bede-23d67bb79351" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e663d-6093-76fe-8e2e-37e6d6947f65" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019e663d-6093-762b-bede-23d67bb79351" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_019e663d-6093-7e03-876d-27ca211accaa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e663d-6093-76fe-8e2e-37e6d6947f65" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_019e663d-6093-7e03-876d-27ca211accaa" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFinanceCostsGross_019e663d-6093-781b-b088-a097cdb65de4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DeferredFinanceCostsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e663d-6093-76fe-8e2e-37e6d6947f65" xlink:to="loc_us-gaap_DeferredFinanceCostsGross_019e663d-6093-781b-b088-a097cdb65de4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_way_DebtInstrumentMinimumBaseRate_019e663d-6093-7884-92cc-9dac20ec33bd" xlink:href="way-20260630.xsd#way_DebtInstrumentMinimumBaseRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e663d-6093-76fe-8e2e-37e6d6947f65" xlink:to="loc_way_DebtInstrumentMinimumBaseRate_019e663d-6093-7884-92cc-9dac20ec33bd" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_way_DebtInstrumentBasisSpreadOnVariableRateAdjustmentPeriod_019e663d-6093-73da-a73a-e1531d479786" xlink:href="way-20260630.xsd#way_DebtInstrumentBasisSpreadOnVariableRateAdjustmentPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e663d-6093-76fe-8e2e-37e6d6947f65" xlink:to="loc_way_DebtInstrumentBasisSpreadOnVariableRateAdjustmentPeriod_019e663d-6093-73da-a73a-e1531d479786" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_019e663d-6093-75e8-ae80-1529e952cdc9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentInterestRateEffectivePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e663d-6093-76fe-8e2e-37e6d6947f65" xlink:to="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_019e663d-6093-75e8-ae80-1529e952cdc9" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.waystar.com/role/DebtScheduleofDebtInstrumentsDetails" xlink:type="simple" xlink:href="way-20260630.xsd#DebtScheduleofDebtInstrumentsDetails"/>
  <link:definitionLink xlink:role="http://www.waystar.com/role/DebtScheduleofDebtInstrumentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019e663d-6093-794c-8956-27b96c737551" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_019e663d-6093-7570-9312-2524a9523b7e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e663d-6093-794c-8956-27b96c737551" xlink:to="loc_us-gaap_DebtInstrumentTable_019e663d-6093-7570-9312-2524a9523b7e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019e663d-6093-7e2b-9fe8-8047357ccbb6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019e663d-6093-7570-9312-2524a9523b7e" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019e663d-6093-7e2b-9fe8-8047357ccbb6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019e663d-6093-7e2b-9fe8-8047357ccbb6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019e663d-6093-7e2b-9fe8-8047357ccbb6" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019e663d-6093-7e2b-9fe8-8047357ccbb6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019e663d-6093-7a08-b632-5ad09639144e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019e663d-6093-7e2b-9fe8-8047357ccbb6" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019e663d-6093-7a08-b632-5ad09639144e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_019e663d-6093-7159-bfe1-fa67a48c7da0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019e663d-6093-7a08-b632-5ad09639144e" xlink:to="loc_us-gaap_LineOfCreditMember_019e663d-6093-7159-bfe1-fa67a48c7da0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_019e663d-6093-76db-9b66-735f498b1806" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019e663d-6093-7570-9312-2524a9523b7e" xlink:to="loc_us-gaap_CreditFacilityAxis_019e663d-6093-76db-9b66-735f498b1806" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019e663d-6093-76db-9b66-735f498b1806_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_019e663d-6093-76db-9b66-735f498b1806" xlink:to="loc_us-gaap_CreditFacilityDomain_019e663d-6093-76db-9b66-735f498b1806_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019e663d-6093-7a51-a28f-70bbcedacf31" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_019e663d-6093-76db-9b66-735f498b1806" xlink:to="loc_us-gaap_CreditFacilityDomain_019e663d-6093-7a51-a28f-70bbcedacf31" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_way_FirstLienTermLoanFacilityMember_019e663d-6093-70ce-8868-ff6a23dca7a5" xlink:href="way-20260630.xsd#way_FirstLienTermLoanFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019e663d-6093-7a51-a28f-70bbcedacf31" xlink:to="loc_way_FirstLienTermLoanFacilityMember_019e663d-6093-70ce-8868-ff6a23dca7a5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_way_ReceivablesFacilityMember_019e663d-6093-7b4a-bf6d-2766e468440e" xlink:href="way-20260630.xsd#way_ReceivablesFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019e663d-6093-7a51-a28f-70bbcedacf31" xlink:to="loc_way_ReceivablesFacilityMember_019e663d-6093-7b4a-bf6d-2766e468440e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_019e663d-6093-7306-9e00-95986effacaa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e663d-6093-794c-8956-27b96c737551" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_019e663d-6093-7306-9e00-95986effacaa" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFinanceCostsNet_019e663d-6093-7a0a-839c-a3447afd5b74" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DeferredFinanceCostsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e663d-6093-794c-8956-27b96c737551" xlink:to="loc_us-gaap_DeferredFinanceCostsNet_019e663d-6093-7a0a-839c-a3447afd5b74" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtCurrent_019e663d-6093-72ed-a484-275b36431366" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebtCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e663d-6093-794c-8956-27b96c737551" xlink:to="loc_us-gaap_LongTermDebtCurrent_019e663d-6093-72ed-a484-275b36431366" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtNoncurrent_019e663d-6093-7c90-9e4c-ae96ebe7d2e2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebtNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e663d-6093-794c-8956-27b96c737551" xlink:to="loc_us-gaap_LongTermDebtNoncurrent_019e663d-6093-7c90-9e4c-ae96ebe7d2e2" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.waystar.com/role/DebtAdditionalInformationDetails" xlink:type="simple" xlink:href="way-20260630.xsd#DebtAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://www.waystar.com/role/DebtAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019e663d-6093-7f40-bf15-d2671f10ca30" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_019e663d-6093-76c7-b99b-a8b7e958dd08" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e663d-6093-7f40-bf15-d2671f10ca30" xlink:to="loc_us-gaap_DebtInstrumentTable_019e663d-6093-76c7-b99b-a8b7e958dd08" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019e663d-6093-79bb-ac4d-281b24c1cbe9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019e663d-6093-76c7-b99b-a8b7e958dd08" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019e663d-6093-79bb-ac4d-281b24c1cbe9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019e663d-6093-79bb-ac4d-281b24c1cbe9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019e663d-6093-79bb-ac4d-281b24c1cbe9" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019e663d-6093-79bb-ac4d-281b24c1cbe9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019e663d-6093-7c6f-81be-b05e7dff30d9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019e663d-6093-79bb-ac4d-281b24c1cbe9" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019e663d-6093-7c6f-81be-b05e7dff30d9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_019e663d-6093-7055-afc0-023d94ee29db" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019e663d-6093-7c6f-81be-b05e7dff30d9" xlink:to="loc_us-gaap_LineOfCreditMember_019e663d-6093-7055-afc0-023d94ee29db" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_019e663d-6093-7d04-941f-54e9ad83ba9f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019e663d-6093-76c7-b99b-a8b7e958dd08" xlink:to="loc_us-gaap_CreditFacilityAxis_019e663d-6093-7d04-941f-54e9ad83ba9f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019e663d-6093-7d04-941f-54e9ad83ba9f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_019e663d-6093-7d04-941f-54e9ad83ba9f" xlink:to="loc_us-gaap_CreditFacilityDomain_019e663d-6093-7d04-941f-54e9ad83ba9f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019e663d-6093-711d-973a-d28b47d336a1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_019e663d-6093-7d04-941f-54e9ad83ba9f" xlink:to="loc_us-gaap_CreditFacilityDomain_019e663d-6093-711d-973a-d28b47d336a1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_019e663d-6093-77b5-af18-71f0d5c5c3f7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019e663d-6093-711d-973a-d28b47d336a1" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_019e663d-6093-77b5-af18-71f0d5c5c3f7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebtMember_019e663d-6093-7044-96a4-517ca54d89a1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019e663d-6093-711d-973a-d28b47d336a1" xlink:to="loc_us-gaap_SecuredDebtMember_019e663d-6093-7044-96a4-517ca54d89a1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019e663d-6093-7313-ad91-7da4dc76812b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019e663d-6093-76c7-b99b-a8b7e958dd08" xlink:to="loc_us-gaap_DebtInstrumentAxis_019e663d-6093-7313-ad91-7da4dc76812b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019e663d-6093-7313-ad91-7da4dc76812b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019e663d-6093-7313-ad91-7da4dc76812b" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019e663d-6093-7313-ad91-7da4dc76812b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019e663d-6093-7524-9ad1-5f6d50b69c6d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019e663d-6093-7313-ad91-7da4dc76812b" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019e663d-6093-7524-9ad1-5f6d50b69c6d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_way_February2026FirstLienPaydownMember_019e663d-6093-7f66-aaf7-e4148bb23a75" xlink:href="way-20260630.xsd#way_February2026FirstLienPaydownMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e663d-6093-7524-9ad1-5f6d50b69c6d" xlink:to="loc_way_February2026FirstLienPaydownMember_019e663d-6093-7f66-aaf7-e4148bb23a75" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_019e663d-6093-7b2d-9476-465f2b61f676" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e663d-6093-7f40-bf15-d2671f10ca30" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_019e663d-6093-7b2d-9476-465f2b61f676" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019e663d-6093-729b-8db7-2abf973d181e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e663d-6093-7f40-bf15-d2671f10ca30" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019e663d-6093-729b-8db7-2abf973d181e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_way_DebtInstrumentMinimumBaseRate_019e663d-6093-75ed-a1e4-567eff315b93" xlink:href="way-20260630.xsd#way_DebtInstrumentMinimumBaseRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e663d-6093-7f40-bf15-d2671f10ca30" xlink:to="loc_way_DebtInstrumentMinimumBaseRate_019e663d-6093-75ed-a1e4-567eff315b93" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_way_DebtInstrumentBasisSpreadOnVariableRateAdjustmentPeriod_019e663d-6093-7d64-8c51-3f12df6fe886" xlink:href="way-20260630.xsd#way_DebtInstrumentBasisSpreadOnVariableRateAdjustmentPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e663d-6093-7f40-bf15-d2671f10ca30" xlink:to="loc_way_DebtInstrumentBasisSpreadOnVariableRateAdjustmentPeriod_019e663d-6093-7d64-8c51-3f12df6fe886" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_019e663d-6093-728f-9ece-1bdffc0d5c58" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentInterestRateEffectivePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e663d-6093-7f40-bf15-d2671f10ca30" xlink:to="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_019e663d-6093-728f-9ece-1bdffc0d5c58" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfLongTermLinesOfCredit_019e663d-6093-7c7e-8fad-2d6bb19b4049" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RepaymentsOfLongTermLinesOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e663d-6093-7f40-bf15-d2671f10ca30" xlink:to="loc_us-gaap_RepaymentsOfLongTermLinesOfCredit_019e663d-6093-7c7e-8fad-2d6bb19b4049" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_019e663d-6093-789f-8526-59cd6b4b874b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e663d-6093-7f40-bf15-d2671f10ca30" xlink:to="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_019e663d-6093-789f-8526-59cd6b4b874b" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_019e663d-6093-7762-bf82-8c9c2279dba4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e663d-6093-7f40-bf15-d2671f10ca30" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_019e663d-6093-7762-bf82-8c9c2279dba4" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_way_DebtInstrumentPeriodicPaymentNumberOfInstallments_019e663d-6093-78bf-8e81-0d77f85bf8ea" xlink:href="way-20260630.xsd#way_DebtInstrumentPeriodicPaymentNumberOfInstallments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e663d-6093-7f40-bf15-d2671f10ca30" xlink:to="loc_way_DebtInstrumentPeriodicPaymentNumberOfInstallments_019e663d-6093-78bf-8e81-0d77f85bf8ea" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_way_DebtInstrumentPeriodicPaymentNumberOfRemainingPayments_019e663d-6093-7607-96fc-117c118e0c32" xlink:href="way-20260630.xsd#way_DebtInstrumentPeriodicPaymentNumberOfRemainingPayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e663d-6093-7f40-bf15-d2671f10ca30" xlink:to="loc_way_DebtInstrumentPeriodicPaymentNumberOfRemainingPayments_019e663d-6093-7607-96fc-117c118e0c32" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFinanceCostsNet_019e663d-6093-7454-b25d-ceb5d47e4fcf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DeferredFinanceCostsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e663d-6093-7f40-bf15-d2671f10ca30" xlink:to="loc_us-gaap_DeferredFinanceCostsNet_019e663d-6093-7454-b25d-ceb5d47e4fcf" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtIssuanceCostsLineOfCreditArrangementsNet_019e663d-6093-7564-bfcc-2d0b284875c7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtIssuanceCostsLineOfCreditArrangementsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e663d-6093-7f40-bf15-d2671f10ca30" xlink:to="loc_us-gaap_DebtIssuanceCostsLineOfCreditArrangementsNet_019e663d-6093-7564-bfcc-2d0b284875c7" xlink:type="arc" order="11"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.waystar.com/role/DerivativeFinancialInstrumentsInterestRateSwapsorCapsDesignatedasHedgingInstrumentsDetails" xlink:type="simple" xlink:href="way-20260630.xsd#DerivativeFinancialInstrumentsInterestRateSwapsorCapsDesignatedasHedgingInstrumentsDetails"/>
  <link:definitionLink xlink:role="http://www.waystar.com/role/DerivativeFinancialInstrumentsInterestRateSwapsorCapsDesignatedasHedgingInstrumentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_019e663d-6093-7780-a7dc-98390eee82b3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTable_019e663d-6093-7777-8a29-f4c25c6c1d78" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_019e663d-6093-7780-a7dc-98390eee82b3" xlink:to="loc_us-gaap_DerivativeTable_019e663d-6093-7777-8a29-f4c25c6c1d78" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019e663d-6093-7f74-bd3e-439a24a93607" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_019e663d-6093-7777-8a29-f4c25c6c1d78" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019e663d-6093-7f74-bd3e-439a24a93607" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e663d-6093-7f74-bd3e-439a24a93607_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e663d-6093-7f74-bd3e-439a24a93607" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e663d-6093-7f74-bd3e-439a24a93607_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e663d-6093-7917-b3fb-9a80c54f11c1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e663d-6093-7f74-bd3e-439a24a93607" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e663d-6093-7917-b3fb-9a80c54f11c1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_way_InterestRateSwapEffectiveMay312023ThroughJanuary312026Member_019e663d-6093-7359-9352-4f78ce210c53" xlink:href="way-20260630.xsd#way_InterestRateSwapEffectiveMay312023ThroughJanuary312026Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e663d-6093-7917-b3fb-9a80c54f11c1" xlink:to="loc_way_InterestRateSwapEffectiveMay312023ThroughJanuary312026Member_019e663d-6093-7359-9352-4f78ce210c53" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_way_InterestRateSwapEffectiveApril12025ThroughJanuary302026Member_019e663d-6093-78c9-b586-3f6d4a3a7a54" xlink:href="way-20260630.xsd#way_InterestRateSwapEffectiveApril12025ThroughJanuary302026Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e663d-6093-7917-b3fb-9a80c54f11c1" xlink:to="loc_way_InterestRateSwapEffectiveApril12025ThroughJanuary302026Member_019e663d-6093-78c9-b586-3f6d4a3a7a54" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_way_InterestRateSwapEffectiveOctober12025ThroughApril302026Member_019e663d-6093-757c-89aa-6f0eedf3349a" xlink:href="way-20260630.xsd#way_InterestRateSwapEffectiveOctober12025ThroughApril302026Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e663d-6093-7917-b3fb-9a80c54f11c1" xlink:to="loc_way_InterestRateSwapEffectiveOctober12025ThroughApril302026Member_019e663d-6093-757c-89aa-6f0eedf3349a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_way_InterestRateSwapOneEffectiveJanuary312026ThroughMarch312027Member_019e663d-6093-708d-bc3e-beaa7a35bf2f" xlink:href="way-20260630.xsd#way_InterestRateSwapOneEffectiveJanuary312026ThroughMarch312027Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e663d-6093-7917-b3fb-9a80c54f11c1" xlink:to="loc_way_InterestRateSwapOneEffectiveJanuary312026ThroughMarch312027Member_019e663d-6093-708d-bc3e-beaa7a35bf2f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_way_InterestRateSwapTwoEffectiveJanuary312026ThroughMarch312027Member_019e663d-6093-7121-ba56-6813d7aa50e5" xlink:href="way-20260630.xsd#way_InterestRateSwapTwoEffectiveJanuary312026ThroughMarch312027Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e663d-6093-7917-b3fb-9a80c54f11c1" xlink:to="loc_way_InterestRateSwapTwoEffectiveJanuary312026ThroughMarch312027Member_019e663d-6093-7121-ba56-6813d7aa50e5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNotionalAmount_019e663d-6093-70db-b020-92867fbe2853" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019e663d-6093-7780-a7dc-98390eee82b3" xlink:to="loc_us-gaap_DerivativeNotionalAmount_019e663d-6093-70db-b020-92867fbe2853" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFixedInterestRate_019e663d-6093-72a9-8c11-2e24a0d6f94a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFixedInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019e663d-6093-7780-a7dc-98390eee82b3" xlink:to="loc_us-gaap_DerivativeFixedInterestRate_019e663d-6093-72a9-8c11-2e24a0d6f94a" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.waystar.com/role/DerivativeFinancialInstrumentsEffectofDerivativeInstrumentsDesignatedasHedgingInstrumentsDetails" xlink:type="simple" xlink:href="way-20260630.xsd#DerivativeFinancialInstrumentsEffectofDerivativeInstrumentsDesignatedasHedgingInstrumentsDetails"/>
  <link:definitionLink xlink:role="http://www.waystar.com/role/DerivativeFinancialInstrumentsEffectofDerivativeInstrumentsDesignatedasHedgingInstrumentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e663d-6093-7cb7-a83c-1cf1f5af91b3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e663d-6093-7a9a-8e6d-cd0af7c78ae1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e663d-6093-7cb7-a83c-1cf1f5af91b3" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e663d-6093-7a9a-8e6d-cd0af7c78ae1" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_019e663d-6093-79c6-b375-2e44237f0a40" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e663d-6093-7a9a-8e6d-cd0af7c78ae1" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_019e663d-6093-79c6-b375-2e44237f0a40" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019e663d-6093-79c6-b375-2e44237f0a40_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019e663d-6093-79c6-b375-2e44237f0a40" xlink:to="loc_us-gaap_EquityComponentDomain_019e663d-6093-79c6-b375-2e44237f0a40_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019e663d-6093-7b01-9166-138857fc9269" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019e663d-6093-79c6-b375-2e44237f0a40" xlink:to="loc_us-gaap_EquityComponentDomain_019e663d-6093-7b01-9166-138857fc9269" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember_019e663d-6093-7a1c-9254-162797bdc630" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e663d-6093-7b01-9166-138857fc9269" xlink:to="loc_us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember_019e663d-6093-7a1c-9254-162797bdc630" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OciBeforeReclassificationsNetOfTaxAttributableToParent_019e663d-6093-7f08-b394-cf60e4b6901d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OciBeforeReclassificationsNetOfTaxAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e663d-6093-7cb7-a83c-1cf1f5af91b3" xlink:to="loc_us-gaap_OciBeforeReclassificationsNetOfTaxAttributableToParent_019e663d-6093-7f08-b394-cf60e4b6901d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAociCurrentPeriodBeforeTaxAttributableToParent_019e663d-6093-79fa-8ea0-5716816ae880" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ReclassificationFromAociCurrentPeriodBeforeTaxAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e663d-6093-7cb7-a83c-1cf1f5af91b3" xlink:to="loc_us-gaap_ReclassificationFromAociCurrentPeriodBeforeTaxAttributableToParent_019e663d-6093-79fa-8ea0-5716816ae880" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseNonoperating_019e663d-6093-711c-b6ef-e80e940c0462" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestExpenseNonoperating"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e663d-6093-7cb7-a83c-1cf1f5af91b3" xlink:to="loc_us-gaap_InterestExpenseNonoperating_019e663d-6093-711c-b6ef-e80e940c0462" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.waystar.com/role/RelatedPartyTransactionsDetails" xlink:type="simple" xlink:href="way-20260630.xsd#RelatedPartyTransactionsDetails"/>
  <link:definitionLink xlink:role="http://www.waystar.com/role/RelatedPartyTransactionsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionLineItems_019e663d-6093-7849-9500-f747b8f7e07b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_019e663d-6093-7757-a7f6-c4d03d244e38" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_019e663d-6093-7849-9500-f747b8f7e07b" xlink:to="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_019e663d-6093-7757-a7f6-c4d03d244e38" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019e663d-6093-7804-8a56-70578d7a941e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_019e663d-6093-7757-a7f6-c4d03d244e38" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019e663d-6093-7804-8a56-70578d7a941e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_019e663d-6093-7804-8a56-70578d7a941e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019e663d-6093-7804-8a56-70578d7a941e" xlink:to="loc_us-gaap_RelatedPartyDomain_019e663d-6093-7804-8a56-70578d7a941e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_019e663d-6093-7e46-9e12-57ddd2174c76" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019e663d-6093-7804-8a56-70578d7a941e" xlink:to="loc_us-gaap_RelatedPartyDomain_019e663d-6093-7e46-9e12-57ddd2174c76" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_AffiliatedEntityMember_019e663d-6093-7ca9-a5ed-041755b7e256" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_AffiliatedEntityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_019e663d-6093-7e46-9e12-57ddd2174c76" xlink:to="loc_srt_AffiliatedEntityMember_019e663d-6093-7ca9-a5ed-041755b7e256" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019e663d-6093-7e00-b0a1-3bf0e1b0086b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_019e663d-6093-7757-a7f6-c4d03d244e38" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019e663d-6093-7e00-b0a1-3bf0e1b0086b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019e663d-6093-7e00-b0a1-3bf0e1b0086b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019e663d-6093-7e00-b0a1-3bf0e1b0086b" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019e663d-6093-7e00-b0a1-3bf0e1b0086b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019e663d-6093-785a-99c1-05fe07e18468" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019e663d-6093-7e00-b0a1-3bf0e1b0086b" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019e663d-6093-785a-99c1-05fe07e18468" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_019e663d-6093-704a-b42c-8cdd19945ff0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019e663d-6093-785a-99c1-05fe07e18468" xlink:to="loc_us-gaap_LineOfCreditMember_019e663d-6093-704a-b42c-8cdd19945ff0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_019e663d-6093-7fd9-a3c0-c771aad1ab99" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_019e663d-6093-7757-a7f6-c4d03d244e38" xlink:to="loc_us-gaap_CreditFacilityAxis_019e663d-6093-7fd9-a3c0-c771aad1ab99" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019e663d-6093-7fd9-a3c0-c771aad1ab99_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_019e663d-6093-7fd9-a3c0-c771aad1ab99" xlink:to="loc_us-gaap_CreditFacilityDomain_019e663d-6093-7fd9-a3c0-c771aad1ab99_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019e663d-6093-751d-bbe4-d0c02315bdb9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_019e663d-6093-7fd9-a3c0-c771aad1ab99" xlink:to="loc_us-gaap_CreditFacilityDomain_019e663d-6093-751d-bbe4-d0c02315bdb9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_way_FirstLienTermLoanFacilityMember_019e663d-6093-7b5e-b99e-3b24b5b398d0" xlink:href="way-20260630.xsd#way_FirstLienTermLoanFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019e663d-6093-751d-bbe4-d0c02315bdb9" xlink:to="loc_way_FirstLienTermLoanFacilityMember_019e663d-6093-7b5e-b99e-3b24b5b398d0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_019e663d-6093-75ed-8bb7-ada8a260f49e" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_019e663d-6093-7757-a7f6-c4d03d244e38" xlink:to="loc_srt_CounterpartyNameAxis_019e663d-6093-75ed-8bb7-ada8a260f49e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019e663d-6093-75ed-8bb7-ada8a260f49e_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_019e663d-6093-75ed-8bb7-ada8a260f49e" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019e663d-6093-75ed-8bb7-ada8a260f49e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019e663d-6093-7a73-9676-566e417343f4" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_019e663d-6093-75ed-8bb7-ada8a260f49e" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019e663d-6093-7a73-9676-566e417343f4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_way_BainCapitalLPMember_019e663d-6093-7157-97f3-b706e59d8a60" xlink:href="way-20260630.xsd#way_BainCapitalLPMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019e663d-6093-7a73-9676-566e417343f4" xlink:to="loc_way_BainCapitalLPMember_019e663d-6093-7157-97f3-b706e59d8a60" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_way_AdventMember_019e663d-6093-7f28-9cce-7862c84c3b13" xlink:href="way-20260630.xsd#way_AdventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019e663d-6093-7a73-9676-566e417343f4" xlink:to="loc_way_AdventMember_019e663d-6093-7f28-9cce-7862c84c3b13" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_019e663d-6093-7cd3-af86-9be46204af35" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_019e663d-6093-7849-9500-f747b8f7e07b" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_019e663d-6093-7cd3-af86-9be46204af35" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseNonoperating_019e663d-6093-731f-a4e5-e2d2bbcd5cbc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestExpenseNonoperating"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_019e663d-6093-7849-9500-f747b8f7e07b" xlink:to="loc_us-gaap_InterestExpenseNonoperating_019e663d-6093-731f-a4e5-e2d2bbcd5cbc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019e663d-6093-742c-9f83-3f76767af3d3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_019e663d-6093-7849-9500-f747b8f7e07b" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019e663d-6093-742c-9f83-3f76767af3d3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_way_RevenueEarnedNumberOfClients_019e663d-6093-7352-9eea-b648f45cafc4" xlink:href="way-20260630.xsd#way_RevenueEarnedNumberOfClients"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_019e663d-6093-7849-9500-f747b8f7e07b" xlink:to="loc_way_RevenueEarnedNumberOfClients_019e663d-6093-7352-9eea-b648f45cafc4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_way_NumberOfVendors_019e663d-6093-7e26-9ee5-03a58f7097cf" xlink:href="way-20260630.xsd#way_NumberOfVendors"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_019e663d-6093-7849-9500-f747b8f7e07b" xlink:to="loc_way_NumberOfVendors_019e663d-6093-7e26-9ee5-03a58f7097cf" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfGoodsAndServiceExcludingDepreciationDepletionAndAmortization_019e663d-6093-709c-ae14-77205d79a879" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CostOfGoodsAndServiceExcludingDepreciationDepletionAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_019e663d-6093-7849-9500-f747b8f7e07b" xlink:to="loc_us-gaap_CostOfGoodsAndServiceExcludingDepreciationDepletionAndAmortization_019e663d-6093-709c-ae14-77205d79a879" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.waystar.com/role/CommonandPreferredStockAdditionalInformationDetails" xlink:type="simple" xlink:href="way-20260630.xsd#CommonandPreferredStockAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://www.waystar.com/role/CommonandPreferredStockAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockLineItems_019e663d-6093-78c3-af86-816c9c36c672" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable_019e663d-6093-7267-9c12-5edb7e8a126c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfStockByClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfStockLineItems_019e663d-6093-78c3-af86-816c9c36c672" xlink:to="loc_us-gaap_ScheduleOfStockByClassTable_019e663d-6093-7267-9c12-5edb7e8a126c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_019e663d-6093-7b5b-9414-6c131f42d873" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_019e663d-6093-7267-9c12-5edb7e8a126c" xlink:to="loc_us-gaap_StatementClassOfStockAxis_019e663d-6093-7b5b-9414-6c131f42d873" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_019e663d-6093-7b5b-9414-6c131f42d873_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_019e663d-6093-7b5b-9414-6c131f42d873" xlink:to="loc_us-gaap_ClassOfStockDomain_019e663d-6093-7b5b-9414-6c131f42d873_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_019e663d-6093-7a09-b2ad-2605e9b0a14a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_019e663d-6093-7b5b-9414-6c131f42d873" xlink:to="loc_us-gaap_ClassOfStockDomain_019e663d-6093-7a09-b2ad-2605e9b0a14a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_019e663d-6093-7383-b919-128ab0635979" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019e663d-6093-7a09-b2ad-2605e9b0a14a" xlink:to="loc_us-gaap_CommonClassAMember_019e663d-6093-7383-b919-128ab0635979" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesAuthorized_019e663d-6093-7b42-83bb-a2147a57935e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_019e663d-6093-78c3-af86-816c9c36c672" xlink:to="loc_us-gaap_CommonStockSharesAuthorized_019e663d-6093-7b42-83bb-a2147a57935e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockParOrStatedValuePerShare_019e663d-6093-7a67-b123-e69a0ab18c3f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockParOrStatedValuePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_019e663d-6093-78c3-af86-816c9c36c672" xlink:to="loc_us-gaap_CommonStockParOrStatedValuePerShare_019e663d-6093-7a67-b123-e69a0ab18c3f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesAuthorized_019e663d-6093-70bb-972c-cedc15673bf3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_019e663d-6093-78c3-af86-816c9c36c672" xlink:to="loc_us-gaap_PreferredStockSharesAuthorized_019e663d-6093-70bb-972c-cedc15673bf3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockParOrStatedValuePerShare_019e663d-6093-76d6-83d0-8db079f54877" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockParOrStatedValuePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_019e663d-6093-78c3-af86-816c9c36c672" xlink:to="loc_us-gaap_PreferredStockParOrStatedValuePerShare_019e663d-6093-76d6-83d0-8db079f54877" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_way_CommonStockShareReclassified_019e663d-6093-71a1-8786-3229226af8fd" xlink:href="way-20260630.xsd#way_CommonStockShareReclassified"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_019e663d-6093-78c3-af86-816c9c36c672" xlink:to="loc_way_CommonStockShareReclassified_019e663d-6093-71a1-8786-3229226af8fd" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesIssued_019e663d-6093-7ffb-ac58-27308cf3fdf0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_019e663d-6093-78c3-af86-816c9c36c672" xlink:to="loc_us-gaap_CommonStockSharesIssued_019e663d-6093-7ffb-ac58-27308cf3fdf0" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_019e663d-6093-7fbc-bb05-2afd56016df3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_019e663d-6093-78c3-af86-816c9c36c672" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_019e663d-6093-7fbc-bb05-2afd56016df3" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StockRepurchaseProgramAuthorizedAmount1_019ede9b-2e00-7347-9147-b605f76ded41" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_StockRepurchaseProgramAuthorizedAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_019e663d-6093-78c3-af86-816c9c36c672" xlink:to="loc_srt_StockRepurchaseProgramAuthorizedAmount1_019ede9b-2e00-7347-9147-b605f76ded41" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.waystar.com/role/StockbasedCompensationEquityIncentivePlansAdditionalInformationDetails" xlink:type="simple" xlink:href="way-20260630.xsd#StockbasedCompensationEquityIncentivePlansAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://www.waystar.com/role/StockbasedCompensationEquityIncentivePlansAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6093-76d1-b69a-e122f4b7487d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e663d-6093-76d7-bdb1-dd2022b7b00e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6093-76d1-b69a-e122f4b7487d" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e663d-6093-76d7-bdb1-dd2022b7b00e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_019e663d-6093-73c1-83ba-d6e277d83582" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e663d-6093-76d7-bdb1-dd2022b7b00e" xlink:to="loc_us-gaap_PlanNameAxis_019e663d-6093-73c1-83ba-d6e277d83582" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_019e663d-6093-73c1-83ba-d6e277d83582_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_019e663d-6093-73c1-83ba-d6e277d83582" xlink:to="loc_us-gaap_PlanNameDomain_019e663d-6093-73c1-83ba-d6e277d83582_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_019e663d-6093-7001-8626-2d619cf761da" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_019e663d-6093-73c1-83ba-d6e277d83582" xlink:to="loc_us-gaap_PlanNameDomain_019e663d-6093-7001-8626-2d619cf761da" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_way_StockIncentivePlan2019Member_019e663d-6093-7039-8036-4f4eee8ea0e9" xlink:href="way-20260630.xsd#way_StockIncentivePlan2019Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019e663d-6093-7001-8626-2d619cf761da" xlink:to="loc_way_StockIncentivePlan2019Member_019e663d-6093-7039-8036-4f4eee8ea0e9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_way_EquityIncentivePlan2024Member_019e663d-6093-74ba-8a3a-cff19296567a" xlink:href="way-20260630.xsd#way_EquityIncentivePlan2024Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019e663d-6093-7001-8626-2d619cf761da" xlink:to="loc_way_EquityIncentivePlan2024Member_019e663d-6093-74ba-8a3a-cff19296567a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_way_EmployeeStockPurchasePlan2024Member_019e663d-6093-7e5d-9e69-4fc1c7016a05" xlink:href="way-20260630.xsd#way_EmployeeStockPurchasePlan2024Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019e663d-6093-7001-8626-2d619cf761da" xlink:to="loc_way_EmployeeStockPurchasePlan2024Member_019e663d-6093-7e5d-9e69-4fc1c7016a05" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019e663d-6093-7475-8678-7226b336bcd8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e663d-6093-76d7-bdb1-dd2022b7b00e" xlink:to="loc_us-gaap_AwardTypeAxis_019e663d-6093-7475-8678-7226b336bcd8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6093-7475-8678-7226b336bcd8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019e663d-6093-7475-8678-7226b336bcd8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6093-7475-8678-7226b336bcd8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6093-7d80-a094-7c3c2fe99401" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019e663d-6093-7475-8678-7226b336bcd8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6093-7d80-a094-7c3c2fe99401" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_019e663d-6093-7b0f-95c3-3367fd185665" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6093-7d80-a094-7c3c2fe99401" xlink:to="loc_us-gaap_EmployeeStockOptionMember_019e663d-6093-7b0f-95c3-3367fd185665" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_019e663d-6093-79bc-800f-cb6075f4cd37" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6093-7d80-a094-7c3c2fe99401" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_019e663d-6093-79bc-800f-cb6075f4cd37" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_way_PerformanceStockUnitsWithMarketBasedConditionsMember_019e663d-6093-777b-ac0e-67240ce22b30" xlink:href="way-20260630.xsd#way_PerformanceStockUnitsWithMarketBasedConditionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6093-7d80-a094-7c3c2fe99401" xlink:to="loc_way_PerformanceStockUnitsWithMarketBasedConditionsMember_019e663d-6093-777b-ac0e-67240ce22b30" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_way_PerformanceStockUnitsWithPerformanceBasedConditionsMember_019e663d-6093-7ce6-921d-83874dbbd55b" xlink:href="way-20260630.xsd#way_PerformanceStockUnitsWithPerformanceBasedConditionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6093-7d80-a094-7c3c2fe99401" xlink:to="loc_way_PerformanceStockUnitsWithPerformanceBasedConditionsMember_019e663d-6093-7ce6-921d-83874dbbd55b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockMember_019e663d-6093-7ec4-98bd-3bcd07705fa7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6093-7d80-a094-7c3c2fe99401" xlink:to="loc_us-gaap_EmployeeStockMember_019e663d-6093-7ec4-98bd-3bcd07705fa7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingAxis_019e663d-6093-783d-bd08-e5d5bbb5d61a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_VestingAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e663d-6093-76d7-bdb1-dd2022b7b00e" xlink:to="loc_us-gaap_VestingAxis_019e663d-6093-783d-bd08-e5d5bbb5d61a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingDomain_019e663d-6093-783d-bd08-e5d5bbb5d61a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_VestingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VestingAxis_019e663d-6093-783d-bd08-e5d5bbb5d61a" xlink:to="loc_us-gaap_VestingDomain_019e663d-6093-783d-bd08-e5d5bbb5d61a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingDomain_019e663d-6093-7fe5-a943-b71fbe228f26" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_VestingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VestingAxis_019e663d-6093-783d-bd08-e5d5bbb5d61a" xlink:to="loc_us-gaap_VestingDomain_019e663d-6093-7fe5-a943-b71fbe228f26" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationAwardTrancheOneMember_019e663d-6093-744e-adef-620e2c070989" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationAwardTrancheOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_019e663d-6093-7fe5-a943-b71fbe228f26" xlink:to="loc_us-gaap_ShareBasedCompensationAwardTrancheOneMember_019e663d-6093-744e-adef-620e2c070989" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationAwardTrancheTwoMember_019e663d-6093-7b65-93a6-5f118cce8d61" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationAwardTrancheTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_019e663d-6093-7fe5-a943-b71fbe228f26" xlink:to="loc_us-gaap_ShareBasedCompensationAwardTrancheTwoMember_019e663d-6093-7b65-93a6-5f118cce8d61" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019e663d-6093-7a88-8755-30664643912e" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e663d-6093-76d7-bdb1-dd2022b7b00e" xlink:to="loc_srt_RangeAxis_019e663d-6093-7a88-8755-30664643912e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e663d-6093-7a88-8755-30664643912e_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019e663d-6093-7a88-8755-30664643912e" xlink:to="loc_srt_RangeMember_019e663d-6093-7a88-8755-30664643912e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e663d-6093-70fa-a1cc-cbe2232d5334" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019e663d-6093-7a88-8755-30664643912e" xlink:to="loc_srt_RangeMember_019e663d-6093-70fa-a1cc-cbe2232d5334" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019e663d-6093-70a8-b1c0-18aa50e15623" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019e663d-6093-70fa-a1cc-cbe2232d5334" xlink:to="loc_srt_MinimumMember_019e663d-6093-70a8-b1c0-18aa50e15623" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019e663d-6093-75dc-8fe7-f13d3d678b0e" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019e663d-6093-70fa-a1cc-cbe2232d5334" xlink:to="loc_srt_MaximumMember_019e663d-6093-75dc-8fe7-f13d3d678b0e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_019e663d-6093-7f29-a982-512047e220b0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6093-76d1-b69a-e122f4b7487d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_019e663d-6093-7f29-a982-512047e220b0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_019e663d-6093-7f85-baac-ac934535b936" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6093-76d1-b69a-e122f4b7487d" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_019e663d-6093-7f85-baac-ac934535b936" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_019e663d-6093-7d91-bb7e-6fa5e81073f4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6093-76d1-b69a-e122f4b7487d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_019e663d-6093-7d91-bb7e-6fa5e81073f4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_019e663d-6093-7c0d-b1e0-3db2204104c4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6093-76d1-b69a-e122f4b7487d" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_019e663d-6093-7c0d-b1e0-3db2204104c4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_019e663d-6093-7c86-9ad6-a59e612bc8f9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6093-76d1-b69a-e122f4b7487d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_019e663d-6093-7c86-9ad6-a59e612bc8f9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum_019e663d-6093-7e00-be8d-e6f022768603" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6093-76d1-b69a-e122f4b7487d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum_019e663d-6093-7e00-be8d-e6f022768603" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_way_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardPerformancePeriod_019e663d-6093-7ed6-94bc-526f6d552478" xlink:href="way-20260630.xsd#way_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardPerformancePeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6093-76d1-b69a-e122f4b7487d" xlink:to="loc_way_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardPerformancePeriod_019e663d-6093-7ed6-94bc-526f6d552478" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_019e663d-6093-775a-899c-9e47993d3b30" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockCapitalSharesReservedForFutureIssuance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6093-76d1-b69a-e122f4b7487d" xlink:to="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_019e663d-6093-775a-899c-9e47993d3b30" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_019e663d-6093-710c-8b11-c4b4174240d6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6093-76d1-b69a-e122f4b7487d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_019e663d-6093-710c-8b11-c4b4174240d6" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardDiscountFromMarketPricePurchaseDate_019e663d-6093-7d53-a17c-2c1c0d825fde" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardDiscountFromMarketPricePurchaseDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6093-76d1-b69a-e122f4b7487d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardDiscountFromMarketPricePurchaseDate_019e663d-6093-7d53-a17c-2c1c0d825fde" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_019e663d-6093-7a33-a93c-45b108445853" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6093-76d1-b69a-e122f4b7487d" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_019e663d-6093-7a33-a93c-45b108445853" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_019e663d-6093-7624-98de-27176e0ee5b4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6093-76d1-b69a-e122f4b7487d" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_019e663d-6093-7624-98de-27176e0ee5b4" xlink:type="arc" order="11"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.waystar.com/role/StockbasedCompensationStockOptionsAdditionalInformationDetails" xlink:type="simple" xlink:href="way-20260630.xsd#StockbasedCompensationStockOptionsAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://www.waystar.com/role/StockbasedCompensationStockOptionsAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6093-724b-82a4-e91b7cdc5194" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e663d-6093-75fc-80e1-671d417adc16" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6093-724b-82a4-e91b7cdc5194" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e663d-6093-75fc-80e1-671d417adc16" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019e663d-6093-7d76-baf8-c033db9ba575" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e663d-6093-75fc-80e1-671d417adc16" xlink:to="loc_us-gaap_AwardTypeAxis_019e663d-6093-7d76-baf8-c033db9ba575" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6093-7d76-baf8-c033db9ba575_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019e663d-6093-7d76-baf8-c033db9ba575" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6093-7d76-baf8-c033db9ba575_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6093-71ff-be96-088bbf5a2235" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019e663d-6093-7d76-baf8-c033db9ba575" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6093-71ff-be96-088bbf5a2235" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_019e663d-6093-705e-a109-4baa49061067" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6093-71ff-be96-088bbf5a2235" xlink:to="loc_us-gaap_EmployeeStockOptionMember_019e663d-6093-705e-a109-4baa49061067" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_way_ShareBasedPaymentArrangementTimeBasedOptionMember_019e663d-6093-7e13-a7ec-877f78833d5d" xlink:href="way-20260630.xsd#way_ShareBasedPaymentArrangementTimeBasedOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6093-71ff-be96-088bbf5a2235" xlink:to="loc_way_ShareBasedPaymentArrangementTimeBasedOptionMember_019e663d-6093-7e13-a7ec-877f78833d5d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_019e663d-6093-7caf-ad5a-c1ba71fb82f4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6093-724b-82a4-e91b7cdc5194" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_019e663d-6093-7caf-ad5a-c1ba71fb82f4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_019e663d-6093-744b-95b8-87dc993a4639" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6093-724b-82a4-e91b7cdc5194" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_019e663d-6093-744b-95b8-87dc993a4639" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_019eb0f0-6dcf-74b9-820a-1e89427e6765" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6093-724b-82a4-e91b7cdc5194" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_019eb0f0-6dcf-74b9-820a-1e89427e6765" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber_019e663d-6093-7f44-a68d-5b6eab99b137" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6093-724b-82a4-e91b7cdc5194" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber_019e663d-6093-7f44-a68d-5b6eab99b137" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice_019e663d-6093-794d-ad25-9bead3d12266" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6093-724b-82a4-e91b7cdc5194" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice_019e663d-6093-794d-ad25-9bead3d12266" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue_019e663d-6093-7a82-a15c-a071935083a6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6093-724b-82a4-e91b7cdc5194" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue_019e663d-6093-7a82-a15c-a071935083a6" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerm1_019e663d-6093-783b-85be-b99322dd9629" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6093-724b-82a4-e91b7cdc5194" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerm1_019e663d-6093-783b-85be-b99322dd9629" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_019e663d-6093-7a2b-95a5-11abdaf2824b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6093-724b-82a4-e91b7cdc5194" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_019e663d-6093-7a2b-95a5-11abdaf2824b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_019e663d-6093-7c42-bed5-9f80715a0458" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6093-724b-82a4-e91b7cdc5194" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_019e663d-6093-7c42-bed5-9f80715a0458" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions_019e663d-6093-78df-85cc-53e51c7a5c95" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6093-724b-82a4-e91b7cdc5194" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions_019e663d-6093-78df-85cc-53e51c7a5c95" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_019e663d-6093-70c6-a4f1-efd4f4d2f352" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6093-724b-82a4-e91b7cdc5194" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_019e663d-6093-70c6-a4f1-efd4f4d2f352" xlink:type="arc" order="10"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.waystar.com/role/StockbasedCompensationStockOptionsAssumptionsDetails" xlink:type="simple" xlink:href="way-20260630.xsd#StockbasedCompensationStockOptionsAssumptionsDetails"/>
  <link:definitionLink xlink:role="http://www.waystar.com/role/StockbasedCompensationStockOptionsAssumptionsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6093-7a29-b736-9c238d13aeb8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e663d-6093-7193-bce1-c9765592b783" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6093-7a29-b736-9c238d13aeb8" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e663d-6093-7193-bce1-c9765592b783" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019e663d-6093-795d-b57b-d53cd77b3b36" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e663d-6093-7193-bce1-c9765592b783" xlink:to="loc_us-gaap_AwardTypeAxis_019e663d-6093-795d-b57b-d53cd77b3b36" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6093-795d-b57b-d53cd77b3b36_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019e663d-6093-795d-b57b-d53cd77b3b36" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6093-795d-b57b-d53cd77b3b36_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6093-7c90-bf6f-887a108594b5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019e663d-6093-795d-b57b-d53cd77b3b36" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6093-7c90-bf6f-887a108594b5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_019e663d-6093-77e6-9b47-5a93a56ff61f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6093-7c90-bf6f-887a108594b5" xlink:to="loc_us-gaap_EmployeeStockOptionMember_019e663d-6093-77e6-9b47-5a93a56ff61f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_019e663d-6093-78b5-9594-d176c4d64ae5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6093-7a29-b736-9c238d13aeb8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_019e663d-6093-78b5-9594-d176c4d64ae5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_019e663d-6093-7d87-aaf6-84582cf8ad8e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_019e663d-6093-78b5-9594-d176c4d64ae5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_019e663d-6093-7d87-aaf6-84582cf8ad8e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_019e663d-6093-7bc2-b2c6-df6eff850899" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_019e663d-6093-78b5-9594-d176c4d64ae5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_019e663d-6093-7bc2-b2c6-df6eff850899" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_019e663d-6093-702d-a29e-f1b2e803e3d2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_019e663d-6093-78b5-9594-d176c4d64ae5" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_019e663d-6093-702d-a29e-f1b2e803e3d2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_019e663d-6093-791a-8a7a-6c4110e193a5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_019e663d-6093-78b5-9594-d176c4d64ae5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_019e663d-6093-791a-8a7a-6c4110e193a5" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.waystar.com/role/StockbasedCompensationRSUActivityDetails" xlink:type="simple" xlink:href="way-20260630.xsd#StockbasedCompensationRSUActivityDetails"/>
  <link:definitionLink xlink:role="http://www.waystar.com/role/StockbasedCompensationRSUActivityDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6093-7b2c-921e-d24a2f427dea" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e663d-6093-7c61-94b0-1792698dfe7d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6093-7b2c-921e-d24a2f427dea" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e663d-6093-7c61-94b0-1792698dfe7d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019e663d-6093-739f-9469-460c64d87b60" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e663d-6093-7c61-94b0-1792698dfe7d" xlink:to="loc_us-gaap_AwardTypeAxis_019e663d-6093-739f-9469-460c64d87b60" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6093-739f-9469-460c64d87b60_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019e663d-6093-739f-9469-460c64d87b60" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6093-739f-9469-460c64d87b60_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6093-7b05-84ef-3adc7cc7bef6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019e663d-6093-739f-9469-460c64d87b60" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6093-7b05-84ef-3adc7cc7bef6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_019e663d-6093-77d2-9511-04b26a7b4fa3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6093-7b05-84ef-3adc7cc7bef6" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_019e663d-6093-77d2-9511-04b26a7b4fa3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019e663d-6093-7913-8dc4-c7c2448b77b7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6093-7b2c-921e-d24a2f427dea" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019e663d-6093-7913-8dc4-c7c2448b77b7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_019e663d-6093-732d-a0b6-75834f54e65f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019e663d-6093-7913-8dc4-c7c2448b77b7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_019e663d-6093-732d-a0b6-75834f54e65f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_019e663d-6093-713a-829f-af27d23db9bf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019e663d-6093-7913-8dc4-c7c2448b77b7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_019e663d-6093-713a-829f-af27d23db9bf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_019e663d-6093-78e1-bd1b-c4f0b7a4b418" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019e663d-6093-7913-8dc4-c7c2448b77b7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_019e663d-6093-78e1-bd1b-c4f0b7a4b418" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_019e663d-6093-779d-9fb6-738332a52723" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019e663d-6093-7913-8dc4-c7c2448b77b7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_019e663d-6093-779d-9fb6-738332a52723" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_019e663d-6093-7c05-a27e-2c2bff197231" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019e663d-6093-7134-8350-ddc9e9a367ed" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6093-7b2c-921e-d24a2f427dea" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019e663d-6093-7134-8350-ddc9e9a367ed" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_019e663d-6093-74c3-b51a-db639f38ae79" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019e663d-6093-7134-8350-ddc9e9a367ed" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_019e663d-6093-74c3-b51a-db639f38ae79" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_019e663d-6093-7e05-bfad-f8d8906f0b7c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019e663d-6093-7134-8350-ddc9e9a367ed" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_019e663d-6093-7e05-bfad-f8d8906f0b7c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_019e663d-6093-7d74-8bcf-c0b1ac6d1f23" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019e663d-6093-7134-8350-ddc9e9a367ed" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_019e663d-6093-7d74-8bcf-c0b1ac6d1f23" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_019e663d-6093-724b-b0c0-1bb80f912d95" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019e663d-6093-7134-8350-ddc9e9a367ed" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_019e663d-6093-724b-b0c0-1bb80f912d95" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_019e663d-6093-7a9f-ac07-4d116be0ecf2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.waystar.com/role/StockbasedCompensationRSUsAdditionalInformationDetails" xlink:type="simple" xlink:href="way-20260630.xsd#StockbasedCompensationRSUsAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://www.waystar.com/role/StockbasedCompensationRSUsAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6093-724f-8f4a-f9aa2ae2535e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e663d-6093-7166-969e-ace2f76661ac" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6093-724f-8f4a-f9aa2ae2535e" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e663d-6093-7166-969e-ace2f76661ac" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019e663d-6093-7bf0-a06b-7b3139a763c9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e663d-6093-7166-969e-ace2f76661ac" xlink:to="loc_us-gaap_AwardTypeAxis_019e663d-6093-7bf0-a06b-7b3139a763c9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6093-7bf0-a06b-7b3139a763c9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019e663d-6093-7bf0-a06b-7b3139a763c9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6093-7bf0-a06b-7b3139a763c9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6093-7c2f-96a4-4c2b8cf1b582" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019e663d-6093-7bf0-a06b-7b3139a763c9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6093-7c2f-96a4-4c2b8cf1b582" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_019e663d-6093-757a-9d38-bbc12b571a5b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6093-7c2f-96a4-4c2b8cf1b582" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_019e663d-6093-757a-9d38-bbc12b571a5b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_019e663d-6093-7b6c-9ce4-5059453dce9e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6093-724f-8f4a-f9aa2ae2535e" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_019e663d-6093-7b6c-9ce4-5059453dce9e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_019e663d-6093-7bbd-a4a5-0dc3e1e7cd36" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6093-724f-8f4a-f9aa2ae2535e" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_019e663d-6093-7bbd-a4a5-0dc3e1e7cd36" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.waystar.com/role/StockbasedCompensationPSUsAdditionalInformationDetails" xlink:type="simple" xlink:href="way-20260630.xsd#StockbasedCompensationPSUsAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://www.waystar.com/role/StockbasedCompensationPSUsAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6093-7db4-9b72-118d3e68ba92" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e663d-6093-7a1b-8130-486657fbaef1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6093-7db4-9b72-118d3e68ba92" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e663d-6093-7a1b-8130-486657fbaef1" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019e663d-6093-7d2a-beeb-ee21946bad8a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e663d-6093-7a1b-8130-486657fbaef1" xlink:to="loc_us-gaap_AwardTypeAxis_019e663d-6093-7d2a-beeb-ee21946bad8a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6093-7d2a-beeb-ee21946bad8a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019e663d-6093-7d2a-beeb-ee21946bad8a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6093-7d2a-beeb-ee21946bad8a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6093-78f5-be41-4a28c8ac939b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019e663d-6093-7d2a-beeb-ee21946bad8a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6093-78f5-be41-4a28c8ac939b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_way_PerformanceStockUnitsWithMarketBasedConditionsMember_019e663d-6093-762c-80d8-7aa026d09998" xlink:href="way-20260630.xsd#way_PerformanceStockUnitsWithMarketBasedConditionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6093-78f5-be41-4a28c8ac939b" xlink:to="loc_way_PerformanceStockUnitsWithMarketBasedConditionsMember_019e663d-6093-762c-80d8-7aa026d09998" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_way_PerformanceStockUnitsWithPerformanceBasedConditionsMember_019e663d-6093-7e69-894a-5d052302b283" xlink:href="way-20260630.xsd#way_PerformanceStockUnitsWithPerformanceBasedConditionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6093-78f5-be41-4a28c8ac939b" xlink:to="loc_way_PerformanceStockUnitsWithPerformanceBasedConditionsMember_019e663d-6093-7e69-894a-5d052302b283" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember_019e663d-6093-7d45-b7d9-54cf6570c291" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6093-78f5-be41-4a28c8ac939b" xlink:to="loc_us-gaap_PerformanceSharesMember_019e663d-6093-7d45-b7d9-54cf6570c291" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_019e663d-6093-78c0-9aa9-be6276f07b8f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e663d-6093-7a1b-8130-486657fbaef1" xlink:to="loc_us-gaap_PlanNameAxis_019e663d-6093-78c0-9aa9-be6276f07b8f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_019e663d-6093-78c0-9aa9-be6276f07b8f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_019e663d-6093-78c0-9aa9-be6276f07b8f" xlink:to="loc_us-gaap_PlanNameDomain_019e663d-6093-78c0-9aa9-be6276f07b8f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_019e663d-6093-7453-b120-994ba1b8f44d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_019e663d-6093-78c0-9aa9-be6276f07b8f" xlink:to="loc_us-gaap_PlanNameDomain_019e663d-6093-7453-b120-994ba1b8f44d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_way_EquityIncentivePlan2024Member_019e663d-6093-7d33-8531-9e25dea82ae9" xlink:href="way-20260630.xsd#way_EquityIncentivePlan2024Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019e663d-6093-7453-b120-994ba1b8f44d" xlink:to="loc_way_EquityIncentivePlan2024Member_019e663d-6093-7d33-8531-9e25dea82ae9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019e663d-6093-7771-872f-a2ab3bd2dc42" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e663d-6093-7a1b-8130-486657fbaef1" xlink:to="loc_srt_RangeAxis_019e663d-6093-7771-872f-a2ab3bd2dc42" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e663d-6093-7771-872f-a2ab3bd2dc42_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019e663d-6093-7771-872f-a2ab3bd2dc42" xlink:to="loc_srt_RangeMember_019e663d-6093-7771-872f-a2ab3bd2dc42_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e663d-6093-7c20-a36b-18fb0e14eb18" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019e663d-6093-7771-872f-a2ab3bd2dc42" xlink:to="loc_srt_RangeMember_019e663d-6093-7c20-a36b-18fb0e14eb18" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019e663d-6093-7ec8-b844-522f5f439fcf" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019e663d-6093-7c20-a36b-18fb0e14eb18" xlink:to="loc_srt_MinimumMember_019e663d-6093-7ec8-b844-522f5f439fcf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019e663d-6093-74dc-a199-7ddcdb61d48c" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019e663d-6093-7c20-a36b-18fb0e14eb18" xlink:to="loc_srt_MaximumMember_019e663d-6093-74dc-a199-7ddcdb61d48c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_019e663d-6093-76bd-af8c-6caa8f1c1b79" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6093-7db4-9b72-118d3e68ba92" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_019e663d-6093-76bd-af8c-6caa8f1c1b79" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_019e663d-6093-76b3-8a97-97f0f3305289" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6093-7db4-9b72-118d3e68ba92" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_019e663d-6093-76b3-8a97-97f0f3305289" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_019e663d-6093-7d72-bfa1-c7a8f37958cd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6093-7db4-9b72-118d3e68ba92" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_019e663d-6093-7d72-bfa1-c7a8f37958cd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_way_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardPerformancePeriod_019e663d-6093-7f9a-af64-5a20a0908297" xlink:href="way-20260630.xsd#way_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardPerformancePeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6093-7db4-9b72-118d3e68ba92" xlink:to="loc_way_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardPerformancePeriod_019e663d-6093-7f9a-af64-5a20a0908297" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_019e663d-6168-7077-97b9-7f5063e1bf41" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6093-7db4-9b72-118d3e68ba92" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_019e663d-6168-7077-97b9-7f5063e1bf41" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_019e663d-6168-72eb-b1d3-1073ad81b309" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6093-7db4-9b72-118d3e68ba92" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_019e663d-6168-72eb-b1d3-1073ad81b309" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.waystar.com/role/StockbasedCompensationPSUsValuationAssumptionDetails" xlink:type="simple" xlink:href="way-20260630.xsd#StockbasedCompensationPSUsValuationAssumptionDetails"/>
  <link:definitionLink xlink:role="http://www.waystar.com/role/StockbasedCompensationPSUsValuationAssumptionDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6168-7321-8ca0-c19f11959c95" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e663d-6168-7af4-a029-d940882ae1d3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6168-7321-8ca0-c19f11959c95" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e663d-6168-7af4-a029-d940882ae1d3" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019e663d-6168-7610-b57d-3a82072253d2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e663d-6168-7af4-a029-d940882ae1d3" xlink:to="loc_us-gaap_AwardTypeAxis_019e663d-6168-7610-b57d-3a82072253d2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6168-7610-b57d-3a82072253d2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019e663d-6168-7610-b57d-3a82072253d2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6168-7610-b57d-3a82072253d2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6168-7d7c-957a-0f7be362cd95" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019e663d-6168-7610-b57d-3a82072253d2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6168-7d7c-957a-0f7be362cd95" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember_019e663d-6168-7b6f-9870-96c85cfa735a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6168-7d7c-957a-0f7be362cd95" xlink:to="loc_us-gaap_PerformanceSharesMember_019e663d-6168-7b6f-9870-96c85cfa735a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_019e663d-6168-787f-a4b2-550fe985921b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6168-7321-8ca0-c19f11959c95" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_019e663d-6168-787f-a4b2-550fe985921b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_019e663d-6168-7a85-840d-bfeca998bf5c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6168-7321-8ca0-c19f11959c95" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_019e663d-6168-7a85-840d-bfeca998bf5c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_019e663d-6168-7565-94e7-8916b4ffb29f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6168-7321-8ca0-c19f11959c95" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_019e663d-6168-7565-94e7-8916b4ffb29f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_019e663d-6168-7972-b0dd-7019508be5e7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6168-7321-8ca0-c19f11959c95" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_019e663d-6168-7972-b0dd-7019508be5e7" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.waystar.com/role/StockbasedCompensationPSUActivityDetails" xlink:type="simple" xlink:href="way-20260630.xsd#StockbasedCompensationPSUActivityDetails"/>
  <link:definitionLink xlink:role="http://www.waystar.com/role/StockbasedCompensationPSUActivityDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6168-7bf5-9024-9fee6b20bb2c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e663d-6168-7be6-b9d3-59dc1b1b1f82" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6168-7bf5-9024-9fee6b20bb2c" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e663d-6168-7be6-b9d3-59dc1b1b1f82" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019e663d-6168-780c-bf53-4f1acc6ad1e9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e663d-6168-7be6-b9d3-59dc1b1b1f82" xlink:to="loc_us-gaap_AwardTypeAxis_019e663d-6168-780c-bf53-4f1acc6ad1e9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6168-780c-bf53-4f1acc6ad1e9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019e663d-6168-780c-bf53-4f1acc6ad1e9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6168-780c-bf53-4f1acc6ad1e9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6168-7af8-98d2-9c0813c13901" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019e663d-6168-780c-bf53-4f1acc6ad1e9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6168-7af8-98d2-9c0813c13901" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember_019e663d-6168-78a3-b6a6-0b8fc7cbe130" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6168-7af8-98d2-9c0813c13901" xlink:to="loc_us-gaap_PerformanceSharesMember_019e663d-6168-78a3-b6a6-0b8fc7cbe130" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019e663d-6168-7ae5-a820-420624c96395" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6168-7bf5-9024-9fee6b20bb2c" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019e663d-6168-7ae5-a820-420624c96395" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_019e663d-6168-7341-91b9-6f47646c50c4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019e663d-6168-7ae5-a820-420624c96395" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_019e663d-6168-7341-91b9-6f47646c50c4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_019e663d-6168-7625-ae09-69d3ee66cf1d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019e663d-6168-7ae5-a820-420624c96395" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_019e663d-6168-7625-ae09-69d3ee66cf1d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_019e663d-6168-74d5-9718-a670cb30318e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019e663d-6168-7ae5-a820-420624c96395" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_019e663d-6168-74d5-9718-a670cb30318e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_019e663d-6168-7ec0-bef1-7ed3f89c9680" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019e663d-6168-7ae5-a820-420624c96395" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_019e663d-6168-7ec0-bef1-7ed3f89c9680" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_019e663d-6168-7bad-9657-c93d3686add4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019e663d-6168-7f90-96b0-f233b1c7973c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e663d-6168-7bf5-9024-9fee6b20bb2c" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019e663d-6168-7f90-96b0-f233b1c7973c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_019e663d-6168-7e74-bd3c-a623d63db04c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019e663d-6168-7f90-96b0-f233b1c7973c" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_019e663d-6168-7e74-bd3c-a623d63db04c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_019e663d-6168-7a7f-99bf-151435e022c7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019e663d-6168-7f90-96b0-f233b1c7973c" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_019e663d-6168-7a7f-99bf-151435e022c7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_019e663d-6168-72a5-8549-07c010e0d08d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019e663d-6168-7f90-96b0-f233b1c7973c" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_019e663d-6168-72a5-8549-07c010e0d08d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_019e663d-6168-79f0-b46b-6444928f7066" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019e663d-6168-7f90-96b0-f233b1c7973c" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_019e663d-6168-79f0-b46b-6444928f7066" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_019e663d-6168-7bd7-8c54-57937b7986ef" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.waystar.com/role/StockbasedCompensationStockbasedCompensationExpenseDetails" xlink:type="simple" xlink:href="way-20260630.xsd#StockbasedCompensationStockbasedCompensationExpenseDetails"/>
  <link:definitionLink xlink:role="http://www.waystar.com/role/StockbasedCompensationStockbasedCompensationExpenseDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_019e663d-6168-73b8-bdfe-41883ee50b8d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_019e663d-6168-7a03-bf31-76160e9ca184" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_019e663d-6168-73b8-bdfe-41883ee50b8d" xlink:to="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_019e663d-6168-7a03-bf31-76160e9ca184" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019e663d-6168-7760-8019-6891259bd83a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOfIncomeLocationBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_019e663d-6168-7a03-bf31-76160e9ca184" xlink:to="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019e663d-6168-7760-8019-6891259bd83a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_019e663d-6168-7011-b37d-d0cf6a5ec196" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_019e663d-6168-73b8-bdfe-41883ee50b8d" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_019e663d-6168-7011-b37d-d0cf6a5ec196" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.waystar.com/role/StockbasedCompensationStockbasedCompensationExpenseDetails_1" xlink:type="simple" xlink:href="way-20260630.xsd#StockbasedCompensationStockbasedCompensationExpenseDetails_1"/>
  <link:definitionLink xlink:role="http://www.waystar.com/role/StockbasedCompensationStockbasedCompensationExpenseDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_019e663d-6168-73b8-bdfe-41883ee50b8d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_019e663d-6168-7a03-bf31-76160e9ca184" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_019e663d-6168-73b8-bdfe-41883ee50b8d" xlink:to="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_019e663d-6168-7a03-bf31-76160e9ca184" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_019e663d-6168-7011-b37d-d0cf6a5ec196" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_019e663d-6168-73b8-bdfe-41883ee50b8d" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_019e663d-6168-7011-b37d-d0cf6a5ec196" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.waystar.com/role/IncomePerShareReconciliationoftheNumeratorsandDenominatorsofBasicandDilutedDetails" xlink:type="simple" xlink:href="way-20260630.xsd#IncomePerShareReconciliationoftheNumeratorsandDenominatorsofBasicandDilutedDetails"/>
  <link:definitionLink xlink:role="http://www.waystar.com/role/IncomePerShareReconciliationoftheNumeratorsandDenominatorsofBasicandDilutedDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_way_EarningsPerShareLineItems_019e663d-6168-749a-abae-819b70bbe455" xlink:href="way-20260630.xsd#way_EarningsPerShareLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_way_EarningsPerShareTable_019e663d-6168-700d-9bf1-d6266875e871" xlink:href="way-20260630.xsd#way_EarningsPerShareTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_way_EarningsPerShareLineItems_019e663d-6168-749a-abae-819b70bbe455" xlink:to="loc_way_EarningsPerShareTable_019e663d-6168-700d-9bf1-d6266875e871" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019e663d-6168-7426-bd87-7a88c86c91bb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_way_EarningsPerShareTable_019e663d-6168-700d-9bf1-d6266875e871" xlink:to="loc_us-gaap_AwardTypeAxis_019e663d-6168-7426-bd87-7a88c86c91bb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6168-7426-bd87-7a88c86c91bb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019e663d-6168-7426-bd87-7a88c86c91bb" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6168-7426-bd87-7a88c86c91bb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6168-7ba1-9f75-8c74065fb028" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019e663d-6168-7426-bd87-7a88c86c91bb" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6168-7ba1-9f75-8c74065fb028" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_019e663d-6168-7e71-be3f-87f1110a4401" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6168-7ba1-9f75-8c74065fb028" xlink:to="loc_us-gaap_EmployeeStockOptionMember_019e663d-6168-7e71-be3f-87f1110a4401" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_019e663d-6168-7631-9017-aef684ab7193" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6168-7ba1-9f75-8c74065fb028" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_019e663d-6168-7631-9017-aef684ab7193" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockMember_019e663d-6168-75b6-b153-396abc176b91" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e663d-6168-7ba1-9f75-8c74065fb028" xlink:to="loc_us-gaap_EmployeeStockMember_019e663d-6168-75b6-b153-396abc176b91" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasicAbstract_019e663d-6168-7d8e-ac4b-c3e61c09159b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EarningsPerShareBasicAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_way_EarningsPerShareLineItems_019e663d-6168-749a-abae-819b70bbe455" xlink:to="loc_us-gaap_EarningsPerShareBasicAbstract_019e663d-6168-7d8e-ac4b-c3e61c09159b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019e663d-6168-70ac-b959-ecebe536ccf6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAbstract_019e663d-6168-7d8e-ac4b-c3e61c09159b" xlink:to="loc_us-gaap_NetIncomeLoss_019e663d-6168-70ac-b959-ecebe536ccf6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic_019e663d-6168-736a-b8a0-5aebd835c83b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAbstract_019e663d-6168-7d8e-ac4b-c3e61c09159b" xlink:to="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic_019e663d-6168-736a-b8a0-5aebd835c83b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_019e663d-6168-7160-9ee4-27b527a1abe6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAbstract_019e663d-6168-7d8e-ac4b-c3e61c09159b" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_019e663d-6168-7160-9ee4-27b527a1abe6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic_019e663d-6168-7bc9-8708-37a96612b3f9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EarningsPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAbstract_019e663d-6168-7d8e-ac4b-c3e61c09159b" xlink:to="loc_us-gaap_EarningsPerShareBasic_019e663d-6168-7bc9-8708-37a96612b3f9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDilutedAbstract_019e663d-6168-74f7-832c-59da11e891d3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EarningsPerShareDilutedAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_way_EarningsPerShareLineItems_019e663d-6168-749a-abae-819b70bbe455" xlink:to="loc_us-gaap_EarningsPerShareDilutedAbstract_019e663d-6168-74f7-832c-59da11e891d3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019e663d-6168-750d-bdcd-f347948938bf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLoss"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted_019e663d-6168-71b0-b3c8-c024610dc13a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareDilutedAbstract_019e663d-6168-74f7-832c-59da11e891d3" xlink:to="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted_019e663d-6168-71b0-b3c8-c024610dc13a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_019e663d-6168-7da6-bdd6-5e0e3c9d6b96" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareDilutedAbstract_019e663d-6168-74f7-832c-59da11e891d3" xlink:to="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_019e663d-6168-7da6-bdd6-5e0e3c9d6b96" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_019e663d-6168-7ec2-83d1-5467c0c46d2e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareDilutedAbstract_019e663d-6168-74f7-832c-59da11e891d3" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_019e663d-6168-7ec2-83d1-5467c0c46d2e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_019e663d-6168-72d5-b08b-2d1823c2d36b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareDilutedAbstract_019e663d-6168-74f7-832c-59da11e891d3" xlink:to="loc_us-gaap_EarningsPerShareDiluted_019e663d-6168-72d5-b08b-2d1823c2d36b" xlink:type="arc" order="5"/>
  </link:definitionLink>
</link:linkbase>
