Where does “obest” come from?

obest (Serbo-Croatian) comes from Serbo-Croatian o, from Proto-Slavic o(b), from Proto-Balto-Slavic ab, from Proto-Indo-European h₃ebʰi.

Ancestry of “obest”, step by step

Step	Language	Word	Meaning
1	Serbo-Croatian	o	on, against; about, concerning, of, on
2	Proto-Slavic	o(b)	around, about; concerning; against, on
3	Proto-Balto-Slavic	ab	—
4	Proto-Indo-European	h₃ebʰi	—

obest — Etymology, Origin & Word History | Etymology Explorer