adder , n :
(obsolete) A snake. A name loosely applied to various snakes more or less resembling the viper; a viper. (chiefly Britain) A small venomous serpent of the genus Vipera. The common European adder is the Vipera berus. The puff adders of Africa are species of the genus Oecobius. (US, Canada) Any of several small nonvenomous snakes resembling the adder, such as the milk snake. The sea-stickleback or adder-fish.