Where does “Alltwen” come from?

Alltwen (Welsh) comes from Welsh allt, from Middle Welsh allt, from Proto-Brythonic *alt, from Proto-Celtic altos, from Proto-Indo-European h₂eltós, from Proto-Indo-European h₂él- — to grow, nourish.

Ancestry of “Alltwen”, step by step

Alltwen traces back through two separate lines of ancestry.

via Welsh allt

StepLanguageWordMeaning
1Welshallthillside, slope; wood, small forest
2Middle Welshallt
3Proto-Brythonic*alt
4Proto-Celticaltosheight, cliff
5Proto-Indo-Europeanh₂eltós
6Proto-Indo-Europeanh₂él-to grow, nourish

via Welsh wen

StepLanguageWordMeaning
1WelshwenSoft mutation of gwen
Every word from Proto-Indo-European h₂él-Every word from Proto-Indo-European h₂eltósEvery word from Proto-Celtic altos
Alltwen — Etymology, Origin & Word History | Etymology Explorer