Where does “coul” come from?

coul (Middle Cornish) comes from Proto-Celtic ɸolnos, from Proto-Indo-European polh₁-, from Proto-Indo-European pelh₁- — to fill.

Ancestry of “coul”, step by step

StepLanguageWordMeaning
1Proto-Celticɸolnosgreat in size
2Proto-Indo-Europeanpolh₁-—
3Proto-Indo-Europeanpelh₁-to fill
Every word from Proto-Indo-European pelh₁- →Every word from Proto-Indo-European polh₁- →Every word from Proto-Celtic ɸolnos →