Where does “usitans” come from?

usitans (Latin) comes from Latin usitor, from Latin ūtor, from Proto-Slavic *ǫtorъ, from Proto-Slavic torъ, from Proto-Slavic terti, from Proto-Indo-European terh₁- — to rub, turn; to drill, pierce.

Definitions

Ancestry of “usitans”, step by step

Step	Language	Word	Meaning
1	Latin	usitor	I use habitually
2	Latin	ūtor	to use, make use of, employ
3	Proto-Slavic	*ǫtorъ	croze
4	Proto-Slavic	torъ	paddock, pen
5	Proto-Slavic	terti	to rub, to scrape; to polish
6	Proto-Indo-European	terh₁-	to rub, turn; to drill, pierce

Every word from Proto-Indo-European terh₁- →Every word from Proto-Slavic terti →Every word from Proto-Slavic torъ →