The Collaborative International Dictionary of English v.0.48:

Quadrangle \Quad"ran`gle\, n. [F., fr. L. quadrangulum; quattuor
   four + angulus an angle. See Four, and Angle a corner.]
   [1913 Webster]
   1. (Geom.) A plane figure having four angles, and
      consequently four sides; any figure having four angles.
      [1913 Webster]

   2. A square or quadrangular space or inclosure, such a space
      or court surrounded by buildings, esp. such a court in a
      college or public school in England.
      [1913 Webster]

WordNet (r) 3.0 (2006):

quadrangle
    n 1: a four-sided polygon [syn: quadrilateral, quadrangle,
         tetragon]
    2: a rectangular area surrounded on all sides by buildings [syn:
       quad, quadrangle]