pit viper

pit viper   n.  Any of various venomous snakes of the family Crotalidae, such as a copperhead, rattlesnake, or fer-de-lance, characterized by a small sensory pit below each eye.

Main Entry: pit viper
Function: noun
: any of various mostly New World highly specialized venomous snakes (as the rattlesnake, copperhead, water moccasin, andfer-de-lance) that belong to a subfamily (Crotalinae) of the family Viperidae, that have a small depression on each side of the head between the eye and the nostril, and that have hollow perforatedfangs usually folded back in the upper part of the mouth but erected in striking

pit viper   Any of various very venomous snakes of the family Crotalidae. Pit vipers are characterized by a triangular head with a small sensory pit below each eye. The pits detect infrared radiation and help the snake locate prey. Some scientists classify the pit vipers as a subfamily Crotalinae within the Viperidae, the family of vipers, rather than as a separate family. Copperheads, rattlesnakes, and fer-de-lances are pit vipers.