Where does “inferior” come from?

inferior (Latin) comes from Latin īnferus, from Proto-Indo-European *(H)n̥dʰér.

Ancestry of “inferior”, step by step

Step	Language	Word	Meaning
1	Latin	īnferus	—
2	Proto-Indo-European	*(H)n̥dʰér	—

inferior — Etymology, Origin & Word History | Etymology Explorer