Merriam-Webster Logo
  • Dictionary
  • Thesaurus
  • Scrabble
  • Spanish Central
  • Learner's Dictionary


adjective vi·cious \ˈvi-shəs\

Simple Definition of vicious

  • : very violent and cruel

  • : very dangerous

  • : having or showing very angry or cruel feelings

Source: Merriam-Webster's Learner's Dictionary

Full Definition of vicious

  1. 1 :  having the nature or quality of vice or immorality :  depraved — (see 1vice)

  2. 2 :  defective, faulty; also :  invalid

  3. 3 :  impure, noxious

  4. 4 a :  dangerously aggressive :  savage <a vicious dog> b :  marked by violence or ferocity :  fierce <a vicious fight>

  5. 5 :  malicious, spiteful <vicious gossip>

  6. 6 :  worsened by internal causes that reciprocally augment each other <a vicious wage-price spiral>

viciously adverb
viciousness noun

Examples of vicious in a sentence

  1. Challenging areas of social consensus, however dumb or even vicious the consensus, is largely off limits for the media, because it wins no friends among the general public. —Richard A. Posner, New York Times Book Review, 31 July 2005

  2. The genetically vicious nature of presidential campaigns in America is too obvious to argue with, but some people call it fun, and I am one of them. —Dr. Hunter S. Thompson, Rolling Stone, 11 Nov. 2004

  3. True to Finals form, this hardwood battle has become as vicious as any street scrum. —Anne Marie Cruz, ESPN, 24 June 2002

  4. For most of my life I have retained a haunting image from an old Tarzan movie: piranhas, those vicious little fish with the arrowhead-shaped teeth, devouring a pig. Forget that there are no piranha in Africa. But they do exist in Brazil, in abundance in the meandering waterways of the Amazon Basin. —Gerald Eskenazi, New York Times, 6 October 2002

  5. The Olympics always seemed too much like war, vicious old men manipulating youngsters hungry for fame into performing heroic acts for short change. —Robert Lipsyte, New York Times, 29 July 2001

  6. His slider—a vicious, hard-breaking pitch with which he finished off right-handed hitters for years—was inconsistent and benign, and the velocity of his fastball was diminished. —Buster Olney, New York Times Magazine, 4 March 2001

  7. a vicious tone of voice

  8. I know you're upset with her, but there's no need to be vicious.

Origin of vicious

Middle English, from Anglo-French vicios, from Latin vitiosus full of faults, corrupt, from vitium vice

First Known Use: 14th century

Synonym Discussion of vicious

vicious, villainous, iniquitous, nefarious, corrupt, degenerate mean highly reprehensible or offensive in character, nature, or conduct. vicious may directly oppose virtuous in implying moral depravity, or may connote malignancy, cruelty, or destructive violence <a vicious gangster>. villainous applies to any evil, depraved, or vile conduct or characteristic <a villainous assault>. iniquitous implies absence of all signs of justice or fairness <an iniquitous system of taxation>. nefarious suggests flagrant breaching of time-honored laws and traditions of conduct <the nefarious rackets of organized crime>. corrupt stresses a loss of moral integrity or probity causing betrayal of principle or sworn obligations <city hall was rife with corrupt politicians>. degenerate suggests having sunk to an especially vicious or enervated condition <a degenerate regime propped up by foreign powers>.

VICIOUS Defined for Kids


adjective vi·cious \ˈvi-shəs\

Definition of vicious for Students

  1. 1 :  very dangerous <a vicious dog>

  2. 2 :  filled with or showing unkind feelings <vicious gossip>

  3. 3 :  violent and cruel <a vicious attack>

  4. 4 :  very severe <a vicious storm>

viciously adverb
viciousness noun

Medical Dictionary


adjective vi·cious \ˈvish-əs\

Medical Definition of vicious

  1. 1:  dangerously aggresive <a vicious dog>

  2. 2:  of, relating to, or being perverse or abnormal behavior in a domestic animal

Seen and Heard

What made you want to look up vicious? Please tell us where you read or heard it (including the quote, if possible).


a timid, meek, or unassertive person

Get Word of the Day daily email!


Take a 3-minute break and test your skills!


Which of these is a synonym of nonplus?

disapprove perplex soothe reduce
Name That Thing

Test your visual vocabulary with our 10-question challenge!


Test Your Knowledge - and learn some interesting things along the way.