Where does “cras” come from?

cras (Latin) comes from Proto-Italic krās, from Proto-Indo-European ḱerh₂- — head, top; horn.

Ancestry of “cras”, step by step

Step	Language	Word	Meaning
1	Proto-Italic	krās	—
2	Proto-Indo-European	ḱerh₂-	head, top; horn

cras — Etymology, Origin & Word History | Etymology Explorer