viper

American  

[vahy-per] / ˈvaɪ pər /

noun

vipers plural

1. any of several venomous Old World snakes of the genus Vipera, especially V. berus, a small snake common in northern Eurasia.

2. any related snakes belonging to the family Viperidae, characterized by erectile, venom-conducting fangs.

3. pit viper.

4. any of various venomous or supposedly venomous snakes.

5. a malignant or spiteful person.

6. a false or treacherous person.

7. Military. Viper, a 9-pound (4-kilogram), shoulder-launched, unguided U.S. Army antitank rocket with an effective range of 273 yards (250 meters).

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idioms

1. to nourish a viper in one's bosom, to befriend a person who proves to be treacherous.

viper British  

/ ˈvaɪpə /

noun

1. any venomous Old World snake of the family Viperidae, esp any of the genus Vipera (the adder and related forms), having hollow fangs in the upper jaw that are used to inject venom

2. any of various other snakes, such as the horned viper

3. See pit viper

4. a malicious or treacherous person

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Other Word Forms

Derived Forms

• viper-like
  adjective
• viperish
  adjective
• viperishly
  adverb

Inflected Forms

Nouns

• vipers
  plural

Etymology

Origin of viper

First recorded in 1520–30; from Latin vīpera, variant of unattested vīvipera, noun use of feminine of unattested vīviper, later (as re-formation) vīviparus “bringing forth live young”; see vivi-, -parous

Explanation

A viper is a certain type of poisonous snake. The most common vipers in the United States are rattlesnakes and water moccasins. Vipers are found in most places on earth and they're a diverse group with over 200 species. Vipers have specialized pits on their faces that can detect heat that's emitted from their prey, which gives them a big advantage to sense and catch their prey quickly. Viper is a scientific name for a particular family of snakes that poison others by biting them with hollow fangs that inject venom. And because of that, viper (and snake) are often used to describe spiteful, disloyal, or back-stabbing people.

Example Sentences

See Examples For:

viper vipers

Powell compared China’s naval strategy around Taiwan to that of a boa constrictor, moving slowly to overpower its rival, rather than striking dramatically as a viper might.

From The Wall Street Journal ● Jun. 24, 2026

Their work revealed that the Himalayan pit viper, first described in 1864 and long believed to be a widespread single species, actually represents several deeply distinct evolutionary lineages.

From Science Daily ● May 26, 2026

In 2019, officials at the Chennai airport seized a horned pit viper snake, five Iguanas, four blue-tongued skinks, three green tree frogs and 22 Egyptian tortoises from a man travelling from Thailand.

From BBC ● Jun. 2, 2025

He played Tedros, a wannabe music industry impresario who also happened to be a pseudo-cult-leading viper attracted to the shiny fame of Lily-Rose Depp’s pop star, Jocelyn.

From Salon ● May 19, 2025

He was beginning to feel cold, and slow, as if he had been bitten in the heart by some arctic viper and it was starting to pump its icy venom through his body.

From "The Graveyard Book" by Neil Gaiman

In June, Mumbai customs intercepted two passengers arriving from Thailand with dozens of venomous vipers and more than 100 other creatures, including lizards, sunbirds and tree-climbing possums, also arriving from Thailand.

From Barron's ● Oct. 31, 2025

Confronting her audience, she scolded: "I'll tell you something about my good name / It's mine alone to disgrace / I don't cater to all these vipers dressed in empath's clothing."

From BBC ● Aug. 27, 2025

It is visible to pit vipers as heat, giving them a Predator-like advantage for hunting.

From Salon ● Nov. 16, 2024

Eyelash vipers are famously polychromatic, which means their appearances can vary widely, even among snakes born in the same litter.

From National Geographic ● Feb. 13, 2024

And don’t unnecessarily disturb its beastly cousins nest of vipers and hornet’s nest. can’t see the forest for the trees.

From "Woe Is I" by Patricia T. O'Conner

Related Words

• cobra