- (n.) One who or that which, adds; especially, a machine for adding numbers.
- (n.) A serpent.
- (n.) A small venomous serpent of the genus Vipera. The common European adder is the Vipera (/ Pelias) berus. The puff adders of Africa are species of Clotho.
- (n.) In America, the term is commonly applied to several harmless snakes, as the milk adder, puffing adder, etc.
- (n.) Same as Sea Adder.
Webster's Revised Unabridged Dictionary
| APA | Webster's. (2011). Adder. Retrieved September 22, 2026, from http://smartdefine.org/adder/definitions/1970812 |
| Chicago | Webster's. 2011. "Adder" http://smartdefine.org/adder/definitions/1970812 (accessed September 22, 2026). |
| Harvard | Webster's 2011, Adder, Smart Define, viewed 22 September, 2026, <http://smartdefine.org/adder/definitions/1970812>. |
| MLA | Webster's. "Adder" 27 May 2011. Web. 22 September 2026. <http://smartdefine.org/adder/definitions/1970812> |