- a person who adds numbers
- small terrestrial viper common in northern Eurasia
- In electronics, an adder or summer is a digital circuit that performs addition of numbers. In modern computers adders reside in the arithmetic logic unit (ALU) where other operations are performed. ...
- Adder is a fictional character from the novel series The Animals of Farthing Wood, written by Colin Dann. He appeared in all of the sequels in the series. Adder also made appearances in the animated children's television series The Animals of Farthing Wood based upon the books. ...
- A snake; 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; Any of several small nonvenomous snakes resembling the adder, such as the milk snake
- A poisonous snake of the genus Vipera. The word, unused in the Douay Version, stands in the Authorized Version for four different Hebrew names of serpents.
- a deceitful person will cause trouble, warning
- A unit of rivet shelving designed to connect to a Starter Unit to form a row of shelving. An Adder Unit consists of wo Tee Posts, 4 Double Rivet Beams (for the top and bottom shelves, one each for the front and back), Single Rivet (2 per level) or Double Rivet (4 per level) Beams as needed for ...
- To dream of seeing an adder strike, and a friend, who is dead but seems to be lying down and breathing, rises partly to a sitting position when the adder strikes at him, and then both disappearing into some bushes nearby, denotes that you will be greatly distressed over the ill luck of friends, ...
- add er/The decision to allow another female to participate.
- N (serpent, Vipera) vipuroF, viperoAk
- víbora (see snakes in Spain)