Where does “заплевать” come from?

заплевать (Russian) comes from Russian плева́ть, from Proto-Slavic pľьvati, from Proto-Indo-European (s)ptyēw- — to spit, vomit.

Ancestry of “заплевать”, step by step

Step	Language	Word	Meaning
1	Russian	плева́ть	—
2	Proto-Slavic	pľьvati	to spit
3	Proto-Indo-European	(s)ptyēw-	to spit, vomit

заплевать — Etymology, Origin & Word History | Etymology Explorer