Where does “arca” come from?

arca (Latin) comes from Latin arceo, from Proto-Italic arkeō, from Proto-Indo-European h₂erk- — to protect, guard, hold, lock.

arca (Latin): chest, box, coffer, safe; coffin; ark

Definitions

Step	Language	Word	Meaning
1	Latin	arceo	I shut up, enclose; box in; I keep off, ward off;...
2	Proto-Italic	arkeō	to contain
3	Proto-Indo-European	h₂erk-	to protect, guard, hold, lock