Adder

Adder, a common English name of the Viper (q.v.), but also often more vaguely used for poisonous serpents of the family Viperidæ. A very venomous serpent of New South Wales (Acanthopsis tortor) is sometimes called the Death or Black Adder. In North America various harmless serpents are locally miscalled adders. The word was nædre in Anglo-Saxon; the present form arose through mistaking a nadder for an adder.