Where does “carthenni” come from?

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

Ancestry of “carthenni”, step by step

carthenni traces back through two separate lines of ancestry.

via Welsh i

StepLanguageWordMeaning
1WelshiI, me; to, for; that
2Middle Welshyhis, its with reference to a masculine noun; triggers soft mutation of following consonant
3Old Welshirthe
4Proto-Celticsindosthis
5Proto-Indo-Europeansḗmone
6Proto-Indo-Europeansem-together, one

via Welsh carthen

StepLanguageWordMeaning
1Welshcarthenany sheet, blanket, cloak, etc. made of woven...
2Welshcarthcoarse cloth
3Welshcarthuto cleanse, purge
4Middle Welshcarthu—
5Proto-Brythonic*karθad—
6Proto-Celtic*kartatito clean, wipe
Every word from Proto-Indo-European sem- →Every word from Proto-Indo-European sḗm →Every word from Proto-Celtic sindos →