Where does “orulus” come from?

orulus (Latin) comes from Latin ora, from Latin os, from Proto-Italic ōs, from Proto-Indo-European h₃ésth₁ — bone.

Ancestry of “orulus”, step by step

Step	Language	Word	Meaning
1	Latin	ora	border, rim, frontier, limit, edge; sea coast;...
2	Latin	os	mouth; face, appearance, head; speech
3	Proto-Italic	ōs	—
4	Proto-Indo-European	h₃ésth₁	bone

orulus — Etymology, Origin & Word History | Etymology Explorer