adder Definition

the common venomous viper (Vipera berus) of Europe; broadly : any of various snakes of the viper family

any of several North American snakes (such as the hognose snakes) that are harmless but are popularly believed to be venomous

one that adds; especially : a device (as in a computer) that performs addition

any of a genus (Ophioglossum, family Ophioglossaceae) of small ferns having a spore-bearing stalk resembling a serpent's tongue

dogtooth violet

a large thick-bodied extremely venomous African viper (Bitis arietans)

hognose snake

any of a genus (Heterodon) of rather small harmless stout-bodied North American colubrid snakes with keeled scales and an upturned snout that seldom bite but hiss wildly and often play dead when disturbed —called also hog-nosed snake, puff adder