Source : Webster's Revised Unabridged Dictionary (1913)

Grouse \Grouse\, n. sing. & pl. [Prob. after the analogy of
   mouse, mice, fr. the earlier grice, OF. griesche meor hen:
   cf. F. piegri[`e]che shrike.] (Zo["o]l.)
   Any of the numerous species of gallinaceous birds of the
   family {Tetraonid[ae]}, and subfamily {Tetraonin[ae]},
   inhabiting Europe, Asia, and North America. They have plump
   bodies, strong, well-feathered legs, and usually mottled
   plumage. The group includes the ptarmigans ({Lagopus}),
   having feathered feet.

   Note: Among the European species are the red grouse ({Lagopus
         Scoticus}) and the hazel grouse ({Bonasa betulina}).
         See {Capercaidzie}, {Ptarmigan}, and {Heath grouse}.
         Among the most important American species are the
         ruffed grouse, or New England partridge ({Bonasa
         umbellus}); the sharp-tailed grouse ({Pedioc[ae]tes
         phasianellus}) of the West; the dusky blue, or pine
         grouse ({Dendragapus obscurus}) of the Rocky Mountains;
         the Canada grouse, or spruce partridge ({D.
         Canadensis}). See also {Prairie hen}, and {Sage cock}.
         The Old World sand grouse ({Pterocles}, etc.) belong to
         a very different family. See {Pterocletes}, and {Sand
         grouse}.