nōmenclātor (nōmencŭlātor, Mart. 10, 30, 23; Suet. Aug. 19; id. Calig. 41; id. Claud. 34), ōris, m. [nomen-calo], one who calls a person or thing by name, a nomenclator; among the Romans, a slave who attended his master in canvassing and on similar occasions, for the purpose of telling him the names of those he met in the street, Cic. Att. 4, 1, 5; id. Mur. 36, 37: nomenclatori memoriae loco audacia est, Sen. Ben. 1, 3, 10; id. Ep. 19, 11; id. Ben. 6, 33, 4.
Under the emperors, a slave who told his master the names of the other slaves: servorum causā nomenclator adhibendus, Plin. 33, 1, 6, § 26.