Where does “cyto-” come from?

cyto- (English) comes from Ancient Greek κύτος, from Proto-Indo-European (s)kewH- — to cover, bedeck; cover.

cyto- (English): cell

Definitions

Step	Language	Word	Meaning
1	Ancient Greek	κύτος	a hollow; any vessel; e.g. a jar, an urn, a vase,...
2	Proto-Indo-European	(s)kewH-	to cover, bedeck; cover

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