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

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Example Sentences

See Examples For:

adder

One man’s fixation is another man’s repulsive, venomous puff adder.

From The Wall Street Journal ● Aug. 4, 2026

Symptoms of adder bites in dogs include pain and swelling, bruising, lethargy, drooling and vomiting.

From BBC ● Apr. 24, 2026

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

To investigate, Ms. Folwell set about dissecting the tail of a female death adder.

From New York Times ● Dec. 13, 2022

The sawed plank and the puff adder preyed on his mind.

From "The Teacher’s Funeral" by Richard Peck

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