- the common European viper, Vipera berus.
- any of various other venomous or harmless snakes resembling the viper.
- a person or thing that adds.
- Also called: viper a common viper, Vipera berus, that is widely distributed in Europe, including Britain, and Asia and is typically dark greyish in colour with a black zigzag pattern along the back
- any of various similar venomous or nonvenomous snakes
- a person or thing that adds, esp a single element of an electronic computer, the function of which is to add a single digit of each of two inputs
Old English næddre “a snake, serpent, viper,” from West Germanic *nædro “a snake” (cf. Old Norse naðra, Middle Dutch nadre, Old High German natra, German Natter, Gothic nadrs), from PIE root *netr- (cf. Latin natrix “water snake,” probably by folk-association with nare “to swim;” Old Irish nathir, Welsh neidr “adder”).
The modern form represents a faulty separation 14c.-16c. into an adder, for which see also apron, auger, nickname, humble pie, umpire. Nedder is still a northern English dialect form. Folklore connection with deafness is via Psalm lviii:1-5. The adder is said to stop up its ears to avoid hearing the snake charmer called in to drive it away. Adderbolt (late 15c.) was a former name for “dragonfly.”