Lewis & Short

classĭārĭus, i, m. [classis, 1. B. 2.], pertaining to the navy: centurio, a captain of a ship, Tac. A. 14, 8; cf. Inscr. Orell. 3617.
More freq. as subst.: classĭārĭi, ōrum, m., marines, naval forces, Caes. B. C. 3, 100; Nep. Milt. 7, 3; id. Them. 3, 2; Tac. A. 4, 27; 12, 56; 15, 51; Suet. Tib. 62; id. Galb. 12; id. Oth. 8; id. Vesp. 8.