Where does “patent” come from?

patent (Middle French) comes from Old French patent, from Latin patēns, from Latin pateō, from Proto-Indo-European peth₂- — to spread out; to fly.

Ancestry of “patent”, step by step

Step	Language	Word	Meaning
1	Old French	patent	—
2	Latin	patēns	—
3	Latin	pateō	—
4	Proto-Indo-European	peth₂-	to spread out; to fly

patent — Etymology, Origin & Word History | Etymology Explorer