Where does “-ou” come from?

-ou (Old Welsh) comes from Proto-Brythonic -ow, from Proto-Celtic -owes.

Ancestry of “-ou”, step by step

StepLanguageWordMeaning
1Proto-Brythonic-ow—
2Proto-Celtic-owes—

Words derived from “-ou”

Every word from Proto-Celtic -owes →Every word from Proto-Brythonic -ow →
-ou — Etymology, Origin & Word History | Etymology Explorer