Where does “terne” come from?

terne (Middle French) comes from Old French terne, from Latin ternas, from Latin terni, from Latin ter, from Latin terr, from Old Latin tris, from Proto-Italic trēs, from Proto-Indo-European *tréyes.

Ancestry of “terne”, step by step

Step	Language	Word	Meaning
1	Old French	terne	dull, dim
2	Latin	ternas	accusative feminine plural of terni
3	Latin	terni	three each; three at a time
4	Latin	ter	thrice
5	Latin	terr	—
6	Old Latin	tris	—
7	Proto-Italic	trēs	three
8	Proto-Indo-European	*tréyes	—

Words derived from “terne”

terne
terne
teerling
tern

Every word from Proto-Indo-European *tréyes →Every word from Proto-Italic trēs →Every word from Old Latin tris →