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”; vivi-, -parous

Example Sentences

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

Even if you’re pretty sure it was the viper, doctors will likely wait to see whether you develop symptoms before giving you the drug—a delay that could cost you a limb or even your life.

From Science Magazine • Mar. 8, 2024

Even as you read this, Arteaga’s group is gathering evidence that there’s at least one more eyelash viper species to add to the ranks.

From National Geographic • Feb. 13, 2024

A serpent-tongued viper might call these true believers goobers, rubes, suckers, and dupes, but what good would it do?

From Salon • Jan. 30, 2024

She selected a jade one in the shape of a viper, paid for it, and handed the blue velvet box to Jule.

From "Genuine Fraud" by E. Lockhart

Related Words

• cobra