Source : Webster's Revised Unabridged Dictionary (1913)

Longhorn \Long"horn`\, n. (Zo["o]l.)
   A long-horned animal, as a cow, goat, or beetle. See
   {Long-horned}.

Source : WordNet®

longhorn
     n : long-horned beef cattle formerly common in southwestern
         United States [syn: {Texas longhorn}]