The Collaborative International Dictionary of English v.0.48:

Cirque \Cirque\, n. [F., fr. L. circus.]
   [1913 Webster]
   1. A circle; a circus; a circular erection or arrangement of
      objects.
      [1913 Webster]

            A dismal cirque
            Of Druid stones upon a forlorn moor.  --Keats.
      [1913 Webster]

   2. A kind of circular valley in the side of a mountain,
      walled around by precipices of great height.
      [1913 Webster]

WordNet (r) 3.0 (2006):

cirque
    n 1: a steep-walled semicircular basin in a mountain; may
         contain a lake [syn: cirque, corrie, cwm]