Lewis & Short

ā̆phractus, i, f., or ā̆phractum, i, n., = ἄφρακτος (uncovered, sc. ναῦς, hence), a long vessel without a deck (in pure Latin, navis aperta; only in Cic.): Navigavimus tardius propter aphractorum Rhodiorum imbecillitatem, Cic. Att. 5, 13, 1: detraxit viginti ipsos dies aphractus Rhodiorum, id. ib. 6, 8, 4: aphracta Rhodiorum habebam, id. ib. 5, 11, 4; so id. ib. 5, 12, 1.