Where does “torh₂no-” come from?

torh₂no- (Proto-Indo-European) comes from Proto-Indo-European terh₁- — to rub, turn; to drill, pierce.

Ancestry of “torh₂no-”, step by step

Step	Language	Word	Meaning
1	Proto-Indo-European	terh₁-	to rub, turn; to drill, pierce

torh₂no- — Etymology, Origin & Word History | Etymology Explorer