Where does “sto” come from?

sto (Latin) comes from Proto-Italic staēō, from Proto-Indo-European sth₂éh₁yeti, from Proto-Indo-European *steh₂-.

Ancestry of “sto”, step by step

Step	Language	Word	Meaning
1	Proto-Italic	staēō	stand
2	Proto-Indo-European	sth₂éh₁yeti	—
3	Proto-Indo-European	*steh₂-	—

sto — Etymology, Origin & Word History | Etymology Explorer