(obsolete) Any snake. / (chiefly Britain) A small venomous serpent of the genus Vipera / The puff adders, of Africa (genus Bitis). / (US, Canada) Any of several small nonvenomous snakes resembling adders

Someone who or something which performs arithmetic addition; a machine for adding numbers. / An electronic device that adds voltages, currents or frequencies. / Something which adds or increases.

plural of adder

(Oxford University slang, archaic) Addison's Walk, Magdalen College, Oxford.

(archaic) A dragonfly.

Alternative form of adder's tongue

plural of adder's tongue

Any of several ferns in the genus Ophioglossum, whose spores are produced on a spike resembling a serpent's tongue.

The non-venomous European ringed snake or water snake, Natrix natrix. / The venomous American cottonmouth, Agkistrodon piscivorus. / The non-venomous American northern water snake,Nerodia sipedon

Synonym of adderwort