A venomous snake in the family Viperidae. / (informal) Any venomous snake. / (figuratively) A dangerous, treacherous, or malignant person. / (slang) A person who smokes marijuana.

of or pertaining to a viper / venomous, malicious or treacherous

plural of viper

In a viperous manner.

The quality of being viperous.

Any of various venomous snakes, of the subfamily Crotalinae, found in Asia and the Americas, with a deep pit or fossa on either side of the head that enables them to detect prey by infrared.

plural of pit viper

A large venomous viper, Bitis gabonica, found in African rainforests.

plural of Gaboon viper

The venomous viper Daboia russelii.