Where does “un” come from?

un (Old Breton) comes from Proto-Brythonic ʉn, from Proto-Celtic oinos, from Proto-Indo-European óynos — one; single.

Ancestry of “un”, step by step

StepLanguageWordMeaning
1Proto-Brythonicʉnone
2Proto-Celticoinosone
3Proto-Indo-Europeanóynosone; single

Words derived from “un”

Every word from Proto-Indo-European óynos →Every word from Proto-Celtic oinos →Every word from Proto-Brythonic ʉn →
un — Etymology, Origin & Word History | Etymology Explorer