Middle English word bataille comes from Proto-Indo-European *bū-, Proto-Indo-European *bhau(t)-

Detailed word origin of bataille

Dictionary entry	Language	Definition
*bū-	Proto-Indo-European (ine-pro)
*bhau(t)-	Proto-Indo-European (ine-pro)
battuo	Latin (lat)	I bang (have sex with). I beat, hit, pound, beat up. I fight.
battālia	Late Latin (LL)
bataille	Old French (fro)	Battle.
bataille	Middle English (enm)	Battle.

Words with the same origin as bataille