Where does “муравьиный” come from?

муравьиный (Russian) comes from Russian мураве́й, from Proto-Slavic morvъ, from Proto-Balto-Slavic *marwís, from Proto-Indo-European morwís.

муравьиный (Russian): ant; antlike

Definitions

Step	Language	Word	Meaning
1	Russian	мураве́й	—
2	Proto-Slavic	morvъ	ant
3	Proto-Balto-Slavic	*marwís	—
4	Proto-Indo-European	morwís	—

муравьиный — Etymology, Origin & Word History | Etymology Explorer