Where does “срѣдьнъ” come from?
срѣдьнъ (Old Church Slavonic) comes from Proto-Slavic serdьnъ, from Proto-Slavic serda, from Proto-Balto-Slavic śerd-, from Proto-Indo-European ḱerd- — heart.
срѣдьнъ (Old Church Slavonic) comes from Proto-Slavic serdьnъ, from Proto-Slavic serda, from Proto-Balto-Slavic śerd-, from Proto-Indo-European ḱerd- — heart.