Where does “вередъ” come from?

вередъ (Old East Slavic) comes from Proto-Slavic verdъ, from Proto-Indo-European werdʰ- — to grow; to raise.

Ancestry of “вередъ”, step by step

Step	Language	Word	Meaning
1	Proto-Slavic	verdъ	wart, wound; harm, malice
2	Proto-Indo-European	werdʰ-	to grow; to raise

вередъ — Etymology, Origin & Word History | Etymology Explorer