adder
Concise Oxford English Dictionary © 2008 Oxford University Press:
adder1
▶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 adder, puff adder.
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.
Concise Oxford English Dictionary © 2008 Oxford University Press:
adder2
▶noun Electronics a unit which adds together two input variables.
'adder' also found in these Oxford entries:
