1. 
2. 
[syn: orthogonal, rectangular]
The Collaborative International Dictionary of English v.0.48:
Rectangular \Rec*tan"gu*lar\ (r?k*t?n"g?*l?r), a. [CF. F.
   rectangulaire.]
   Right-angled; having one or more angles of ninety degrees. --
   Rec*tan"gu*lar*ly (r?k*t?n"g?*l?r*l?), adv. --
   Rec*tan"gu*lar*ness, n.
   [1913 Webster]
WordNet (r) 3.0 (2006):
rectangular
    adj 1: having four right angles; "a rectangular figure twice as
           long as it is wide"
    2: having a set of mutually perpendicular axes; meeting at right
       angles; "wind and sea may displace the ship's center of
       gravity along three orthogonal axes"; "a rectangular
       Cartesian coordinate system" [syn: orthogonal,
       rectangular]
Moby Thesaurus II by Grady Ward, 1.0:
31 Moby Thesaurus words for "rectangular":
   cube-shaped, cubed, cubic, cubiform, cuboid, diced, elliptical,
   elongated, foursquare, normal, oblong, oblongated, oblongitudinal,
   orthodiagonal, orthogonal, orthometric, perpendicular,
   quadrangular, quadrate, quadriform, quadrilateral, rhombic,
   rhomboid, right-angle, right-angled, right-angular, square,
   tetragonal, tetrahedral, trapezohedral, trapezoid