water adder

from The Collaborative International Dictionary of English v.0.48

Water adder \Wa"ter ad"der\ (Zool.)
      (a) The water moccasin.
      (b) The common, harmless American water snake
          ({Tropidonotus sipedon}). See Illust. under {Water
          Snake}.
          [1913 Webster]

from The Collaborative International Dictionary of English v.0.48

Water moccasin \Wa"ter moc"ca*sin\ (Zool.)
   A venomous North American snake ({Ancistrodon piscivorus})
   allied to the rattlesnake but destitute of a rattle. It lives
   in or about pools and ponds, and feeds largely of fishes.
   Called also {water snake}, {water adder}, {water viper}.
   [1913 Webster]