| Quadrilateral 1. (a.) Having four sides, and consequently four angles; quadrangular. 2. (n.) A plane figure having four sides, and consequently four angles; a quadrangular figure; any figure formed by four lines. 3. (n.) An area defended by four fortresses supporting each other; as, the Venetian quadrilateral, comprising Mantua, Peschiera, Verona, and Legnano. Thesaurus Entries bifacial, bilateral, biquadratic, cube-shaped, cubed, cubic, cubiform, cuboid, diced, dihedral, flanked, four, four-legged, four-rayed, foursquare, handed, lateral, many-sided, multilateral, oblong, one-sided, orthogonal, polyhedral, quadrangular, quadrate, quadric, quadriform, quadrinomial, quadrivalent, quadruped, quartic, quartile, quaternary, rectangular, rhombic, rhomboid, sided, square, tetractinal, tetrad, tetragonal, tetrahedral, tetravalent, three-sided, trapezohedral, trapezoid, trihedral, trilateral, triquetrous, two-sided, unilateral |