Where does “betulo” come from?

betulo (Esperanto) comes from Latin betula, from Gaulish bitu, from Proto-Celtic betwiyos, from Proto-Indo-European gʷét-.

betulo (Esperanto): birch

Definitions

Step	Language	Word	Meaning
1	Latin	betula	birch tree
2	Gaulish	bitu	—
3	Proto-Celtic	betwiyos	—
4	Proto-Indo-European	gʷét-	—

betulo — Etymology, Origin & Word History | Etymology Explorer