Galleass \Gal"le*ass\ (?; 135), n. [F. gal['e]asse, gal['e]ace; cf. It. galeazza, Sp. galeaza; LL. galea a galley. See {Galley}.] (Naut.) A large galley, having some features of the galleon, as broadside guns; esp., such a vessel used by the southern nations of Europe in the 16th and 17th centuries. See {Galleon}, and {Galley}. [Written variously {galeas}, {gallias}, etc.]
Note: ``The galleasses . . . were a third larger than the ordinary galley, and rowed each by three hundred galley slaves. They consisted of an enormous towering structure at the stern, a castellated structure almost equally massive in front, with seats for the rowers amidships.'' --Motley.