Where does “отверну́ть” come from?

отверну́ть (Russian) comes from Russian верну́ть, from Russian верте́ть, from Proto-Slavic vьrtě̀ti — to turn; turn; to rotate.

Ancestry of “отверну́ть”, step by step

Step	Language	Word	Meaning
1	Russian	верну́ть	—
2	Russian	верте́ть	to turn, to twist
3	Proto-Slavic	vьrtě̀ti	to turn; turn; to rotate

отверну́ть — Etymology, Origin & Word History | Etymology Explorer