Source : Webster's Revised Unabridged Dictionary (1913)

Blacktail \Black"tail`\, n. [Black + tail.]
   1. (Zo["o]l.) A fish; the ruff or pope.

   2. (Zo["o]l.) The black-tailed deer ({Cervus or Cariacus
      Columbianus}) of California and Oregon; also, the mule
      deer of the Rocky Mountains. See {Mule deer}.

Source : WordNet®

blacktail
     n : mule deer of western Rocky Mountains [syn: {black-tailed
         deer}, {blacktail deer}, {Odocoileus hemionus columbianus}]