Where does “betume” come from?

betume (Old Portuguese) comes from Latin bitumen, from Gaulish bitu, from Proto-Celtic betwiyos, from Proto-Indo-European gʷét- — resin, gum.

Ancestry of “betume”, step by step

StepLanguageWordMeaning
1Latinbitumenmineral pitch, bitumen
2Gaulishbitu—
3Proto-Celticbetwiyos—
4Proto-Indo-Europeangʷét-resin, gum
Every word from Proto-Indo-European gʷét- →Every word from Proto-Celtic betwiyos →Every word from Gaulish bitu →
betume — Etymology, Origin & Word History | Etymology Explorer