Where does “dubu” come from?

dubu (Esperanto) comes from Esperanto dubi, from Latin dubitō, from Latin dubō, from Latin *dubos, from Indo-European *bʰuH-.

dubu (Esperanto): imperative of dubi

Definitions

Step	Language	Word	Meaning
1	Esperanto	dubi	to doubt; to question
2	Latin	dubitō	to waver (in opinion), be uncertain, doubt, question, be in doubt
3	Latin	dubō	—
4	Latin	*dubos	—
5	Indo-European	*bʰuH-	—