Where does “oriens” come from?

oriens (Latin) comes from Latin orior, from Proto-Indo-European h₃ér-.

Ancestry of “oriens”, step by step

Step	Language	Word	Meaning
1	Latin	orior	I rise, get up; I appear, become visible; I am...
2	Proto-Indo-European	h₃ér-	—

oriens — Etymology, Origin & Word History | Etymology Explorer