Where does “dʰubno-” come from?

dʰubno- (Proto-Indo-European) comes from Proto-Indo-European dʰewb- — deep, hollow; depths, hollow, deep, bottom.

Ancestry of “dʰubno-”, step by step

Step	Language	Word	Meaning
1	Proto-Indo-European	dʰewb-	deep, hollow; depths, hollow, deep, bottom

dʰubno- — Etymology, Origin & Word History | Etymology Explorer