1) Cottonmouth 2) Dangerous swamp snake 3) Terror of the bayou 4) Venomous semiaquatic creature 5) Venomous semiaquatic snake 6) Venomous swamp slitherer 
• 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.
(from the article `moccasin`) either of two venomous aquatic New World snakes of the viper family (Viperidae): the water moccasin (Agkistrodon piscivorus) or the Mexican moccasin ...
Wa'ter moc'ca·sin (Zoology) 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 . 
[n] - venomous semiaquatic snake of swamps in southern United States 2. [n] - any of numerous North American water snakes inhabiting fresh waters
cottonmouth moccasin noun venomous semiaquatic snake of swamps in southern United States