Lewis Short
(adjective) : quādrĭangŭlus, a, um, quattuor-angulus
* Four-cornered, quadrangular (post-Aug.); figura,Plin. 13, 22, 38, § 118: herba quadriangulo caule,id. 25, 6, 27, § 63: membrum,Aus. Epigr. 128. — As subst.: quădrĭangŭlum, i, n., a quadrilateral figure, quadrangle, Prisc. Fig. Num. p. 417; cf. quadrangulum.
Charlton T. Lewis, Charles Short, A Latin Dictionary