viper

viper — noun

1. a type of poisonous snake with a broad, triangular head and long hollow fangs th

1.nounB1
Definition

a type of poisonous snake with a broad, triangular head and long hollow fangs that fold back against the roof of its mouth when not in use. Vipers inject venom into the animals they bite in order to kill or paralyse them.

Example

Hari spotted a viper coiled under a bush near the hiking trail.

The horned viper is one of the most common venomous snakes in North Africa.

countable noun in generic reference: 'the horned viper'

Common collocations
  • venomous viper
  • deadly viper
  • viper bite
  • viper venom
  • viper fangs
  • horned viper
  • bush viper
Synonyms
  • adder

    used for certain vipers in Europe and parts of Africa; 'adder' is the common name for the only venomous snake in the UK

  • rattlesnake

    a type of viper found in the Americas, named for the rattle at the end of its tail

  • pit viper

    a subfamily of vipers with heat-sensing pits between the eye and nostril; includes rattlesnakes and copperheads

Usage Note

The word 'viper' refers to a whole family of snakes (Viperidae), not a single species. Learners often use 'viper' loosely for any venomous snake, but specialists distinguish vipers from elapids (such as cobras) by their retractable fangs.

Common Mistakes

A viper is a type of snake that lays eggs.
Most vipers give birth to live young instead of laying eggs.
Unlike many snakes, vipers are ovoviviparous; the female keeps the eggs inside her body until they hatch.

2. a person who is cruel, dishonest, and secretly tries to harm others, especially

2.nounC1
Definition

a person who is cruel, dishonest, and secretly tries to harm others, especially people who think they can trust that person. The word compares someone's behaviour to the hidden danger of a viper's bite.

Example

The other staff soon realised that their friendly new manager was a viper.

metaphor: 'was a viper' — describing a person as a snake

Salma called her former business partner a viper after he stole client money.

Common collocations
  • a viper in one's midst
  • a viper in the nest
  • nourish a viper in one's bosom
Synonyms
  • backstabber

    more informal and direct; describes someone who betrays a trusting relationship

  • traitor

    specifically someone who betrays a country, group, or cause; stronger and more political

  • snake

    the same metaphor but more common in everyday English; 'snake' is broader and slightly less dramatic

  • villain

    focuses on evil character rather than specifically on betrayal

Antonyms
  • ally

    someone who supports and stands by you, the opposite of a secret enemy

  • friend

    a person you trust and care about

Usage Note

This figurative sense is much less common in everyday speech than the literal snake meaning. It belongs to a formal or literary register and is often used in political commentary, fiction, or dramatic accusations.

Common Mistakes

My brother is a viper because he forgot my birthday.
The politician turned out to be a viper who betrayed every promise he made.
'Viper' for a person implies deliberate malice and betrayal, not minor faults or carelessness.

Word family

  • viperish
    adjectiveC2

Synonym discussion

Sense: noun/1

'Viper' is a broad family term (Viperidae) for venomous snakes with long, hinged fangs. 'Adder' is the common name used for certain vipers in Europe and Africa — the European adder (Vipera berus) is the only venomous snake native to Britain. 'Rattlesnake' refers specifically to New World vipers that produce a warning rattle with their tail; all rattlesnakes are vipers, but not all vipers have rattles. 'Cobra', by contrast, belongs to a different family (Elapidae) with short, fixed front fangs — they are not vipers. 'Pit viper' is a subfamily (Crotalinae) that includes rattlesnakes, copperheads, and cottonmouths, distinguished by heat-sensing pits between the eye and the nostril. For everyday informal use, speakers often call any venomous snake a 'viper', but in accurate zoological discussion these distinctions matter.

adderrattlesnakecobra ↗pit viper

Common collocations

Nouns

  • viper venom
  • viper bite
  • viper fangs
  • viper species

Phrases

  • a viper in one's bosom
  • a viper in the nest
  • viper pit

Prepositions

  • viper in [place/group]

Etymology

LatinOld FrenchEnglish

'Viper' entered English around the 1500s from Old French 'vipere', which came from Latin 'vipera'. The Latin word is a compound of 'vivus' (alive, living) and 'parere' (to bring forth, to give birth) — because female vipers give birth to live young rather than laying eggs. This live-bearing trait was considered unusual among snakes and became part of the animal's defining description in ancient natural history.