Where does “perthyn” come from?

perthyn (Middle Welsh) comes from Proto-Brythonic *perθɨnɨd, from Latin pertineō, from Latin per, from Latin Ad, from Latin illic, from Latin ille, from Latin olle, from Proto-Italic *olnos — that.

Ancestry of “perthyn”, step by step

StepLanguageWordMeaning
1Proto-Brythonic*perθɨnɨd
2Latinpertineōto extend, stretch out, reach, matter
3Latinperthrough, by means of; throughout, during
4LatinAdtoward, to
5Latinilliche, she, it, yonder, that, overthere; in that...
6Latinillethat; those; "; demonstrative pronoun "; that...
7LatinolleArchaic form of ille
8Proto-Italic*olnosthat

Words derived from “perthyn

Every word from Proto-Italic *olnosEvery word from Latin olleEvery word from Latin ille