Where does “αἰγοθήλης” come from?

αἰγοθήλης (Ancient Greek) comes from Ancient Greek αἴξ, from Proto-Indo-European h₂eyǵ- — goat; oak.

Ancestry of “αἰγοθήλης”, step by step

Step	Language	Word	Meaning
1	Ancient Greek	αἴξ	goat; a kind of waterfowl, possibly a goose; "In...
2	Proto-Indo-European	h₂eyǵ-	goat; oak