Ancistrodon conotortrix

from The Collaborative International Dictionary of English v.0.48

Copperhead \Cop"per*head`\, n. [From its color.]
   1. (Zool.) A poisonous American serpent ({Ancistrodon
      conotortrix}), closely allied to the rattlesnake, but
      without rattles; -- called also {copper-belly}, and {red
      viper}.
      [1913 Webster]

   2. A nickname applied to a person in the Northern States who
      sympathized with the South during the Civil War. [U.S.]
      [1913 Webster]