| any of numerous venomous snakes of the family Crotalidae, of the New World, Asia, and the Malay Archipelago, as the rattlesnake, water moccasin, and copperhead, having a heat-sensitive pit on each side of the head between the eye and nostril. |

| 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. |