Where does “ois” come from?

ois (Old Welsh) comes from Proto-Brythonic oɨs, from Proto-Celtic aiwestom, from Proto-Indo-European h₂ey- — vital force, life, age, eternity; day, morning.

Ancestry of “ois”, step by step

StepLanguageWordMeaning
1Proto-Brythonicoɨsage
2Proto-Celticaiwestomage; lifetime; era
3Proto-Indo-Europeanh₂ey-vital force, life, age, eternity; day, morning

Words derived from “ois”

Every word from Proto-Indo-European h₂ey- →Every word from Proto-Celtic aiwestom →Every word from Proto-Brythonic oɨs →