Where does “ei” come from?

ei (Welsh) comes from Middle Welsh y, from Old Welsh ir, from Proto-Celtic sindos, from Proto-Indo-European sḗm, from Proto-Indo-European sem- — together, one.

ei (Welsh): his, its; him, it; her, its

Definitions

  1. his, its; him, it; her, its

Ancestry of “ei”, step by step

StepLanguageWordMeaning
1Middle Welshyhis, its with reference to a masculine noun; triggers soft mutation of following consonant
2Old Welshirthe
3Proto-Celticsindosthis
4Proto-Indo-Europeansḗmone
5Proto-Indo-Europeansem-together, one
Every word from Proto-Indo-European sem- →Every word from Proto-Indo-European sḗm →Every word from Proto-Celtic sindos →