from The American Heritage® Dictionary of the English Language, 4th Edition

  • adj. Extremely infectious, malignant, or poisonous. Used of a disease or toxin.
  • adj. Capable of causing disease by breaking down protective mechanisms of the host. Used of a pathogen.
  • adj. Bitterly hostile or antagonistic; hateful: virulent criticism. See Synonyms at poisonous.
  • adj. Intensely irritating, obnoxious, or harsh.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • adj. highly infectious, malignant, or deadly.
  • adj. Hostile to the point of being venomous; intensely acrimonious.

from the GNU version of the Collaborative International Dictionary of English

  • adj. Extremely poisonous or venomous; very active in doing injury.
  • adj. Very bitter in enmity; actuated by a desire to injure; malignant.

from The Century Dictionary and Cyclopedia

  • Full of virus; extremely poisonous or venomous.
  • Due to the action of a virus: as, a virulent inoculation.
  • Very bitter or spiteful; malignant: as, a virulent invective; a virulent libel.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • adj. harsh or corrosive in tone
  • adj. extremely poisonous or injurious; producing venom
  • adj. infectious; having the ability to cause disease


Middle English, from Latin vīrulentus, from vīrus, poison.
(American Heritage® Dictionary of the English Language, Fourth Edition)
From Latin virus ("poison, slime, venom"). (Wiktionary)



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  • "Time had been wanton, virulent and spiteful." Money. Amis, Martin.

    September 11, 2011

  • That's an excellent metaphoric use of virulent.

    January 4, 2008

  • "By cunning, cautious; or by nature, cold, 15
    In maiden madness, virulently bold!"
    Sheridan, School for Scandal

    January 2, 2008