Where does “unpertinent” come from?

unpertinent (English) comes from English pertinent, from Middle English pertinent, from Old French pertinent, from Latin pertinens, from Latin pertineō, from Latin per, from Latin Ad, from Latin illic — that.

Ancestry of “unpertinent”, step by step

unpertinent traces back through two separate lines of ancestry.

via English pertinent

StepLanguageWordMeaning
1EnglishpertinentA right that attaches to land, in Scots law
2Middle Englishpertinent
3Old Frenchpertinent
4Latinpertinensextending; pertaining
5Latinpertineōto extend, stretch out, reach, matter
6Latinperthrough, by means of; throughout, during
7LatinAdtoward, to
8Latinilliche, she, it, yonder, that, overthere; in that...
9Latinillethat; those; "; demonstrative pronoun "; that...
10LatinolleArchaic form of ille
11Proto-Italic*olnosthat

via English un

StepLanguageWordMeaning
1EnglishunOne
Every word from Proto-Italic *olnos