n. [ See Add. ] One who, or that which, adds; esp., a machine for adding numbers. [ 1913 Webster ]

n. [ OE. addere, naddere, eddre, AS. nædre, adder, snake; akin to OS. nadra, OHG. natra, natara, Ger. natter, Goth. nadrs, Icel. naðr, masc., naðra, fem.: cf. W. neidr, Gorn. naddyr, Ir. nathair, L. natrix, water snake. An adder is for a nadder. ] 1. A serpent. [ Obs. ] “The eddre seide to the woman.” Wyclif. Gen. iii. 4. ) [ 1913 Webster ]

2. (Zool.) (a) A small venomous serpent of the genus Vipera. The common European adder is the Vipera berus or Pelias berus. The puff adders of Africa are species of Clotho. (b) In America, the term is commonly applied to several harmless snakes, as the milk adder, puffing adder, etc. (c) Same as Sea Adder. [ 1913 Webster ]

☞ In the sculptures the appellation is given to several venomous serpents, -- sometimes to the horned viper (Cerastles). [ 1913 Webster ]

A dragon fly. [ 1913 Webster ]

n. (Bot.) (a) A genus of ferns (Ophioglossum), whose seeds are produced on a spike resembling a serpent's tongue. (b) The yellow dogtooth violet. Gray. [ 1913 Webster ]

n. (Bot.) The common bistort or snakeweed (Polygonum bistorta). [ 1913 Webster ]