Where does “Eochaid” come from?

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

Ancestry of “Eochaid”, step by step

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

Words derived from “Eochaid”

Achaius
Eochaidh
acaio

Every word from Proto-Indo-European h₁oh₁ḱu- →Every word from Proto-Indo-European h₁éḱwos →Every word from Proto-Celtic ekʷos →