Lewis & Short

Ŏnŏmastus, i, m., and -a, ae, f., = Ὀνομαστός, -ή, a Roman surname, Liv. 39, 34; 40, 8; Tac. H. 1, 25; 1, 27; Inscr. Murat. 1144, 1; Inscr. Fabr. p. 751, n. 587.