pit viper

This term refers specifically to a biological classification of snakes. In a scientific or herpetological context, it is used to distinguish these snakes from other vipers by their specialized thermoreceptive organs.

The term is neutral in register but carries a connotation of danger due to the venomous nature of the animals. While the term is used broadly for the subfamily Crotalinae, it is often used interchangeably with "pit viper" in casual conversation to describe any snake possessing these heat-sensing pits.