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A family of poisonous Old World snakes, the true vipers, composed of about 50 species and characterized by two relatively long caniculated fangs at the front of the upper jaw that are attached to movable bones, allowing them to be erect during the bite when the mouth is open, and folded into a palatal skin fold when the jaws are shut.
[L. vipera, viper]
Viperidae(vī-per′ĭ-dē) [L. vipera, snake or serpent + -idea]
The scientific name for a family of venomous snakes found nearly worldwide, having long, hinged fangs allowing deep penetration and injection of venom. The family includes the European viper, gaboon viper, puff adder, Russel viper, and saw-scaled viper.