Where does “ef” come from?

ef (Welsh) comes from Proto-Indo-European éy, from Proto-Indo-European h₁e-.

ef (Welsh): he; him

Definitions

Step	Language	Word	Meaning
1	Proto-Indo-European	éy	the; demonstrative pronoun; this one, he
2	Proto-Indo-European	h₁e-	—

ef — Etymology, Origin & Word History | Etymology Explorer