Where does “गाय” come from?

गाय (Old Marathi) comes from Sanskrit गो, from Proto-Indo-Iranian gāuš, from Proto-Iranian gā́wš, from Proto-Indo-Iranian gā́wš, from Proto-Indo-European gʷṓws — cattle.

Ancestry of “गाय”, step by step

StepLanguageWordMeaning
1Sanskritगोa cow; an ox; cattle, kine, herd of cattle
2Proto-Indo-Iraniangāuš—
3Proto-Iraniangā́wšcow
4Proto-Indo-Iraniangā́wšcow
5Proto-Indo-Europeangʷṓwscattle
Every word from Proto-Indo-European gʷṓws →Every word from Proto-Indo-Iranian gā́wš →Every word from Proto-Iranian gā́wš →