In Europe and Asia, an adder is a small poisonous snake that has a black pattern on its back. In North America, a number of different poisonous and non-poisonous snakes are called adders. = viper. a type of poisonous snake (a nadder, mistaken for an adder; nadder (11-17 centuries) from nAddre). Any of several venomous snakes of the viper family (Viperidae) and the death adder, a viperlike elapid. Vipers include the common adder, puff adders, and night adders. Adders occur in Europe, Asia, Africa, and Australia. They range in length from 18 in. to 5 ft (45 cm to 1.5 m). The puff adder of Africa and the death adder of Australia and the nearby islands are particularly venomous, with a bite potentially lethal to humans. The name is also used for other snakes (e.g., the hognose snake)
{i} common European viper; any of a number of venomous or nonvenomous snakes resembling the viper; person or thing that adds; electronic circuit that sums two numbers in a computer (Computers)
A small venomous serpent of the genus Vipera. The common European adder is the Vipera (or Pelias) berus. The puff adders of Africa are species of the genus Clotho
In America, the term is commonly applied to several harmless snakes, as the milk adder, puffing adder, etc