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

These include the green pit viper commonly found in the northern state of Himachal Pradesh, the Malabar pit viper and hump-nosed pit viper found in southern states and many other species in the north-eastern states.

From BBC ● Feb. 1, 2026

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

The young knight with the green viper embroidered on his surcoat stepped forward and went to one knee.

From "A Game of Thrones" by George R.R. Martin

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

The other class of snake – the vipers – rely more on haemotoxins, which attack the blood, rather than neurotoxins.

From BBC ● May 2, 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

It took Mr. Daley the rest of recess to calm them down and to convince them that there were no pit vipers in Washington State—or anywhere in the United States.

From "I Survived the Eruption of Mount St. Helens, 1980" by Lauren Tarshis

Related Words

• cobra