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.

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