Where does “Aonghas” come from?

Aonghas (Irish) comes from Middle Irish Aengus, from Old Irish Oíngus, from Proto-Celtic *Oinogustus.

Ancestry of “Aonghas”, step by step

Step	Language	Word	Meaning
1	Middle Irish	Aengus	—
2	Old Irish	Oíngus	Angus
3	Proto-Celtic	*Oinogustus	—

Aonghas — Etymology, Origin & Word History | Etymology Explorer