Lewis & Short

Ăgĕlastus, i, m., = ἀγέλαστος (not laughing), a surname of M. Crassus, grandfather of the triumvir of the same name, Plin. 7, 19, 18, § 79; cf. Lucil. ap. Cic. Fin. 5, 30, 92, and Tusc. 3, 15, 31.