Where does “wo” come from?

wo (Primitive Irish) comes from Proto-Celtic uɸo, from Proto-Indo-European upó, from Proto-Indo-European h₃ewp-.

Ancestry of “wo”, step by step

StepLanguageWordMeaning
1Proto-Celticuɸounder, below
2Proto-Indo-Europeanupóunder, below
3Proto-Indo-Europeanh₃ewp-—
Every word from Proto-Indo-European h₃ewp- →Every word from Proto-Indo-European upó →Every word from Proto-Celtic uɸo →