There are 2 main definitions of adder in English:

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adder 1

Pronunciation: /ˈadər/


1A small venomous Eurasian snake that has a dark zigzag pattern on its back and bears live young. Also called viper.
  • Vipera berus, family Viperidae
Example sentences
  • The mating system and spacing pattern of adders largely agree with those of sand lizards.
  • There are also reptiles, like adders or grass snakes, slow-worms and lizards that are prone to fire damage because they cannot get out quickly enough.
  • Along with the loss of heather and cottongrass, birds such as the nightjar, woodlark and stone curlew and animals including the adder, grass snake, and viviparous lizard have been put at risk.
1.1Used in names of snakes that are similar or related to the adder, e.g., death adder, puff adder.
Example sentences
  • A side-winding adder buries itself just beneath the hot sand exposing only its eyes, patiently waiting for unsuspecting prey.
  • The ‘horns’ of his horned adder, resembling a stunning set of false eyelashes, would have drag queens running for cover.


Old English nædre 'serpent, adder', of Germanic origin; related to Dutch adder and German Natter. The initial n was lost in Middle English by wrong division of a naddre; compare with apron, auger, and umpire.

  • One of the words Anglo-Saxons used for a snake was naedre, which became nadder in medieval times. At some point during the 14th or 15th century the word managed to lose its initial n, as people heard ‘a nadder’ and misinterpreted this as ‘an adder’. A northern dialect form nedder still exists. A similar process of ‘wrong division’ took place with words such as apron and umpire ( see pair), and the opposite can happen too, as with, for example, newt and nickname. In time adder became the term for a specific poisonous snake, also known as the viper. The same change nearly happened to the word aunt (Middle English) (which comes from Latin amitia ‘aunt’), for between the 13th and 17th centuries ‘mine aunt’ can appear as ‘my naunt’. In France this change has happened: the word was ante in Old French, but is now tante through the running together of ta ‘your’ and ante. See also deaf.

Words that rhyme with adder

bladder, khaddar, ladder, madder
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There are 2 main definitions of adder in English:

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adder 2

Pronunciation: /ˈadə/

Entry from British & World English dictionary


A unit which adds together two input variables. A full adder can add a bit carried from another addition as well as the two inputs, whereas a half adder can only add the inputs together.
Example sentences
  • An adder adds the difference and the multiplexed signal and outputs therefrom a driving signal to drive the LD.
  • Further, a semiconductor integrated circuit has a dither pattern generator, an adder, and an error distribution unit.
  • Note that multiplication is done using a SINGLE full bit adder, with the carry bit and output fed back in as feedback loops.
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