quadrilateral UK /ˌkwɒdɹɪˈlætəɹəl/US /ˌkwɑdɹəˈlætəɹəl/noun 2adjective 1forms 1 noun2 •A polygon with four sides. •An area defended by four fortresses supporting each other.The Venetian quadrilateral comprised Mantua, Peschiera, Verona, and Legnano. adjective1 •Having four sides.They spoke at a quadrilateral meeting of the trade ministers of the United States, the European Union, Canada, and Japan. formsquadrilaterals
