The DICT Development Group

  Ptarmigan \Ptar"mi*gan\, n. [Gael. tarmachan; cf. Ir. tarmochan,
     tarmonach.] (Zool.)
     Any grouse of the genus Lagopus, of which numerous species
     are known. The feet are completely feathered. Most of the
     species are brown in summer, but turn white, or nearly white,
     in winter.
     [1913 Webster]
  
     Note: They chiefly inhabit the northern countries and high
           mountains of Europe, Asia, and America. The common
           European species is Lagopus mutus. The Scotch grouse,
           red grouse, or moor fowl ({Lagopus Scoticus), is
           reddish brown, and does not turn white in winter. The
           white, or willow, ptarmigan ({Lagopus albus) is found
           in both Europe and America.
           [1913 Webster]

  ptarmigan
      n 1: large Arctic and subarctic grouse with feathered feet and
           usually white winter plumage