adder

¹ American  

[ad-er] / ˈæd ər /

noun

1. the common European viper, Vipera berus.

2. any of various other venomous or harmless snakes resembling the viper.

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adder ² American  

[ad-er] / ˈæd ər /

noun

1. a person or thing that adds.

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adder ¹ British  

/ ˈædə /

noun

1. Also called: viper.  a common viper, Vipera berus, that is widely distributed in Europe, including Britain, and Asia and is typically dark greyish in colour with a black zigzag pattern along the back

2. any of various similar venomous or nonvenomous snakes

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adder ² British  

/ ˈædə /

noun

1. a person or thing that adds, esp a single element of an electronic computer, the function of which is to add a single digit of each of two inputs

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Etymology

Origin of adder¹

before 950; late Middle English; replacing Middle English nadder ( a nadder becoming an adder by misdivision; cf. apron), Old English næddre; cognate with Old Saxon nādra, Old High German nātara ( German Natter ), Old Norse nathra snake, Gothic nadrs adder, Old Irish nathir snake, Latin natrix water snake

Origin of adder²

First recorded in 1570–80; add + -er ¹

Example Sentences

The vet found a small mark but no swelling, which is a common symptom of an adder bite, so was unable to confirm it was the cause.

From BBC • Apr. 24, 2026

In 2025 a reptile, believed to be an adder, was spotted on Morfa'r Garreg beach in Pwllheli, Gwynedd.

From BBC • Apr. 24, 2026

When ElGamel took the number of molecules into account alongside the additional mass, the adder strategy was more precise and less sensitive to mistakes during replication.

From Science Daily • Apr. 17, 2024

Overall, the adder was thought to result in a less precise size distribution.

From Science Daily • Apr. 17, 2024

Suddenly Matthias was face to face with the giant adder.

From "Redwall" by Brian Jacques

Related Words

• cobra