Where does “Achaius” come from?

Achaius (English) comes from Old Irish Eochaid, from Primitive Irish ᚓᚊᚑᚇᚇᚔ, from Proto-Celtic ekʷos, from Proto-Indo-European h₁éḱwos, from Proto-Indo-European h₁oh₁ḱu- — swift.

Ancestry of “Achaius”, step by step

Step	Language	Word	Meaning
1	Old Irish	Eochaid	—
2	Primitive Irish	ᚓᚊᚑᚇᚇᚔ	—
3	Proto-Celtic	ekʷos	horse
4	Proto-Indo-European	h₁éḱwos	stallion, horse
5	Proto-Indo-European	h₁oh₁ḱu-	swift

Every word from Proto-Indo-European h₁oh₁ḱu- →

Achaius — Etymology, Origin & Word History | Etymology Explorer