Where does “επίσημος” come from?

επίσημος (Greek) comes from Ancient Greek ἐπίσημος, from Ancient Greek ἐπί, from Ancient Greek Ἡμέρα, from Ancient Greek ἦμαρ, from Proto-Hellenic ā́mər, from Proto-Indo-European h₂eh₃mr̥, from Proto-Indo-European h₂eh₃- — to be hot; to burn.

επίσημος (Greek): formal, official, authoritative, formal, relating...