Where does “seiz” come from?

seiz (Middle Breton) comes from Old Breton seith, from Proto-Brythonic seiθ, from Proto-Celtic sextam, from Proto-Indo-European septḿ̥ — seven.

Ancestry of “seiz”, step by step

StepLanguageWordMeaning
1Old Bretonseith—
2Proto-Brythonicseiθseven
3Proto-Celticsextamseven
4Proto-Indo-Europeanseptḿ̥seven

Words derived from “seiz”

Every word from Proto-Indo-European septḿ̥ →Every word from Proto-Celtic sextam →Every word from Proto-Brythonic seiθ →