1. Noun.  (obsolete) A snake.
  2. Noun.  (British) A small venomous serpent of the genus ''Vipera''. The common European adder is the ''Vipera'' (or ''Pelias'') ''berus''. The puff adders of Africa are species of the genus ''Clotho''.
  3. Noun.  (US, Canada) Any of several small nonvenomous snakes resembling the adder, such as the milk snake.
  4. Noun.  Someone who or something which performs arithmetic addition.
  5. Noun.  Something which adds or increases.

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This entry was last updated on RefTopia from its source on 3/20/2012.