The Collaborative International Dictionary of English v.0.48:

Wrestling \Wres"tling\, n.
   Act of one who wrestles; specif., the sport consisting of the
   hand-to-hand combat between two unarmed contestants who seek
   to throw each other.

   Note: The various styles of wrestling differ in their
         definition of a fall and in the governing rules. In

   Greco-Roman wrestling, tripping and taking hold of the legs
      are forbidden, and a fall is gained (that is, the bout is
      won), by the contestant who pins both his opponent's
      shoulders to the ground. In

   catch-as-catch-can wrestling, all holds are permitted
      except such as may be barred by mutual consent, and a fall
      is defined as in Greco-Roman style.

   Lancashire style wrestling is essentially the same as
      catch-as-catch-can. In

   Cumberland and Westmorland wrestling the contestants stand
      chest to chest, grasping each other around the body. The
      one first losing his hold, or touching the ground with any
      part of his body except his feet, loses the bout. If both
      fall to the ground at the same time, it is a dogfall, and
      must be wrestled over. In the

   Cornwall and Devon wrestling, the wrestlers complete in
      strong loose linen jackets, catching hold of the jacket,
      or anywhere above the waist. Two shoulders and one hip, or
      two hips and one shoulder, must touch the ground to
      constitute a fall, and if a man is thrown otherwise than
      on his back the contestants get upon their feet and the
      bout recommences.
      [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

Greco-Roman wrestling
    n 1: a style of wrestling where the wrestlers are forbidden to
         tackle or trip or use holds below the waist