Where does “coster” come from?

coster (Middle Dutch) comes from Old French costre, from Latin custor, from Latin cūstos, from Proto-Indo-European (s)kewH- — to cover, bedeck; cover.

Ancestry of “coster”, step by step

Step	Language	Word	Meaning
1	Old French	costre	—
2	Latin	custor	guardian, protector
3	Latin	cūstos	a guard, protector, watchman
4	Proto-Indo-European	(s)kewH-	to cover, bedeck; cover

Words derived from “coster”

koster
koster

Every word from Proto-Indo-European (s)kewH- →Every word from Latin cūstos →Every word from Latin custor →