The Collaborative International Dictionary of English v.0.48:

Ruffed \Ruffed\, a.
   Furnished with a ruff.
   [1913 Webster]

   Ruffed grouse (Zool.), a North American grouse (Bonasa
      umbellus) common in the wooded districts of the Northern
      United States. The male has a ruff of brown or black
      feathers on each side of the neck, and is noted for the
      loud drumming sound he makes during the breeding season.
      Called also tippet grouse, partridge, birch
      partridge, pheasant, drummer, and white-flesher.

   ruffed lemur (Zool.), a species of lemur (lemur varius)
      having a conspicuous ruff on the sides of the head. Its
      color is varied with black and white. Called also ruffed
      maucaco.
      [1913 Webster]

WordNet (r) 3.0 (2006):

ruffed grouse
    n 1: valued as a game bird in eastern United States and Canada
         [syn: ruffed grouse, partridge, Bonasa umbellus]