Where does “οὐαί” come from?

οὐαί (Ancient Greek) comes from Proto-Indo-European wai — oh!; woe!.

οὐαί (Ancient Greek): ah, woe, alas

Definitions

Step	Language	Word	Meaning
1	Proto-Indo-European	wai	oh!; woe!

οὐαί — Etymology, Origin & Word History | Etymology Explorer