Where does “uxsū” come from?

uxsū (Proto-Brythonic) comes from Proto-Celtic uksōn, from Proto-Indo-European uksḗn, from Proto-Indo-European h₂ug-s-ḗn.

Ancestry of “uxsū”, step by step

StepLanguageWordMeaning
1Proto-Celticuksōn—
2Proto-Indo-Europeanuksḗnbull
3Proto-Indo-Europeanh₂ug-s-ḗn—
Every word from Proto-Indo-European h₂ug-s-ḗn →Every word from Proto-Indo-European uksḗn →Every word from Proto-Celtic uksōn →