Where does “avouchier” come from?

avouchier (Old French) comes from Latin advocāre, from Latin Ad, from Latin illic, from Latin ille, from Latin olle, from Proto-Italic *olnos.

Ancestry of “avouchier”, step by step

Step	Language	Word	Meaning
1	Latin	advocāre	—
2	Latin	Ad	—
3	Latin	illic	he, she, it, yonder, that, overthere; in that...
4	Latin	ille	that; those; "; demonstrative pronoun "; that...
5	Latin	olle	Archaic form of ille
6	Proto-Italic	*olnos	—

avouchier — Etymology, Origin & Word History | Etymology Explorer