Where does “dowinis” come from?

dowinis (Proto-Celtic) comes from Proto-Indo-European dʰew- — to die, pass away; to run, flow.

Ancestry of “dowinis”, step by step

Step	Language	Word	Meaning
1	Proto-Indo-European	dʰew-	to die, pass away; to run, flow

dowinis — Etymology, Origin & Word History | Etymology Explorer