Where does “hagio-” come from?

hagio- (French) comes from Ancient Greek ἅγιος, from Proto-Indo-European h₁yaǵ- — to sacrifice; to worship.

Ancestry of “hagio-”, step by step

Step	Language	Word	Meaning
1	Ancient Greek	ἅγιος	devoted to the gods; of things: sacred, holy; of...
2	Proto-Indo-European	h₁yaǵ-	to sacrifice; to worship

hagio- — Etymology, Origin & Word History | Etymology Explorer