The twenty-fourth letter of the Classical and the Modern Greek alphabet, and the twenty-eighth letter of the Old and the Ancient Greek alphabet, i.e. the last letter of every Greek alphabet. Uppercase version: Ω; lowercase: ω.
In omegaverse fiction, a person of a sexually-submissive (and sometimes secondary) gender/sex that is driven by biology, magic, or other means to bond with an alpha, with males of this type often being able to get pregnant.