Where does “*yām-” come from?

*yām- (Proto-Iranian) comes from Proto-Indo-Iranian Yámas, from Proto-Indo-European *yém-o-s.

Ancestry of “*yām-”, step by step

Step	Language	Word	Meaning
1	Proto-Indo-Iranian	Yámas	—
2	Proto-Indo-European	*yém-o-s	—

*yām- — Etymology, Origin & Word History | Etymology Explorer