~ 1
■ noun a small venomous snake which has a dark zigzag pattern on its back and bears live young. [ Vipera berus .]
↘used in names of similar or related snakes, e.g. death ~ , puff ~ .
Word History
Adder comes from the Old English word nædre , 'serpent', from a Germanic root: the n was lost in medieval times through a naddre being read as an addre . Other words formed by a similar process of wrong division include apron , originally a napron , and auger ( a nauger ). The process sometimes works the other way, resulting in n being added to the beginning of a word: a newt was originally an ewt , a nickname an eke-name , and an umpire a noumpere .
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~ 2
■ noun Electronics a unit which adds together two input variables.