Where does “ui” come from?

ui (Old Welsh) comes from Proto-Celtic āwyom, from Proto-Indo-European h₂ōwyóm, from Proto-Indo-European h₂éwis — bird.

Ancestry of “ui”, step by step

StepLanguageWordMeaning
1Proto-Celticāwyomegg
2Proto-Indo-Europeanh₂ōwyómegg
3Proto-Indo-Europeanh₂éwisbird

Words derived from “ui”

Every word from Proto-Indo-European h₂éwis →Every word from Proto-Indo-European h₂ōwyóm →Every word from Proto-Celtic āwyom →