Where does “tes” come from?

tes (Middle Welsh) comes from Proto-Brythonic tes, from Proto-Celtic texstus, from Proto-Indo-European tep- — to be warm, be hot.

Ancestry of “tes”, step by step

StepLanguageWordMeaning
1Proto-Brythonictes—
2Proto-Celtictexstusheat, warmth
3Proto-Indo-Europeantep-to be warm, be hot

Words derived from “tes”

Every word from Proto-Indo-European tep- →Every word from Proto-Celtic texstus →Every word from Proto-Brythonic tes →