viper

American  

[vahy-per] / ˈvaɪ pər /

noun

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

• viper-like
  adjective
• viperish
  adjective
• viperishly
  adverb

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

“Chrysler doesn’t need to come out with a competitor for the Corvette or a Viper or anything like that,” Kyle said.

From The Wall Street Journal • Apr. 4, 2026

Britain said it was sending a warship, HMS Dragon, fitted with a Sea Viper missile system able to launch eight missiles in under 10 seconds.

From Barron's • Mar. 5, 2026

But on the battlefield, she and the rest of the Deadly Viper Assassination Squad are warriors first, women inconsequentially.

From Los Angeles Times • Dec. 5, 2025

Schwaebe says he was seduced by how Unsworth presents on social media: He lives in a large house in Texas, drives a Dodge Viper sports car and, to Schwaebe, kind of resembles Channing Tatum.

From Los Angeles Times • Jul. 14, 2025

Still glued to Gran’s heels, Viper snoozed in a curled ball on the plush carpet.

From "Sir Fig Newton and the Science of Persistence" by Sonja Thomas

Related Words

• cobra