The Collaborative International Dictionary of English v.0.48:

Pintail \Pin"tail`\, n.
   1. (Zool.) A northern duck (Dafila acuta), native of both
      continents. The adult male has a long, tapering tail.
      Called also gray duck, piketail, piket-tail,
      spike-tail, split-tail, springtail, sea pheasant,
      and gray widgeon.
      [1913 Webster]

   2. (Zool.) The sharp-tailed grouse of the great plains and
      Rocky Mountains (Pedioc[ae]tes phasianellus); -- called
      also pintailed grouse, pintailed chicken,
      springtail, and sharptail.
      [1913 Webster]

WordNet (r) 3.0 (2006):

pintail
    n 1: long-necked river duck of the Old and New Worlds having
         elongated central tail feathers [syn: pintail, pin-
         tailed duck, Anas acuta]