Where does “Ὀμφάλη” come from?

Ὀμφάλη (Ancient Greek) comes from Ancient Greek ὀμφαλός, from Proto-Indo-European h₃m̥bʰ-, from Proto-Indo-European h₃nebʰ- — hub; navel.

Ὀμφάλη (Ancient Greek): Omphale, a woman in Greek mythology