Where does “okrajać” come from?

okrajać (Polish) comes from Polish o-, from Old Polish o-, from Proto-Slavic o(b)- — over.

Ancestry of “okrajać”, step by step

Step	Language	Word	Meaning
1	Polish	o-	prefix indicating a perfective verb
2	Old Polish	o-	appears in front of some verbs meaning: to make something behave in a certain way, en-, be-, make
3	Proto-Slavic	o(b)-	over