Where does “cranium” come from?

cranium (Latin) comes from Ancient Greek κρανίον, from Ancient Greek κάρα, from Proto-Hellenic *kárahə.

Ancestry of “cranium”, step by step

Step	Language	Word	Meaning
1	Ancient Greek	κρανίον	skull; head
2	Ancient Greek	κάρα	head, face; the head or top of anything, as of a...
3	Proto-Hellenic	*kárahə	—

cranium — Etymology, Origin & Word History | Etymology Explorer