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

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

From BBC • Apr. 24, 2026

He found the adder method is more precise, researchers have just misunderstood its true nature.

From Science Daily • Apr. 17, 2024

But if something goes wrong using the so-called adder strategy, the cell takes longer to get back to its original size.

From Science Daily • Apr. 17, 2024

They can strike with the venom of an adder when the moment arrives.

From BBC • Apr. 29, 2023

Nervously, she told him about the dead Portuguese and the panga she thought he had given her, about the puff adder that had come from the ancestors, and about Long Teats.

From "A Girl Named Disaster" by Nancy Farmer

Related Words

• cobra