from The American Heritage® Dictionary of the English Language, 5th Edition.

  • adjective Characterized by, causing, or promoting the rapid onset of severe illness. Used of a disease or toxin.
  • adjective Capable of causing disease by aggressively interfering with the immune system of the host. Used of a pathogen.
  • adjective Extremely hostile or malicious.

from The Century Dictionary.

  • 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 the GNU version of the Collaborative International Dictionary of English.

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

from Wiktionary, Creative Commons Attribution/Share-Alike License.

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

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

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


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

[Middle English, from Latin vīrulentus, from vīrus, poison.]

from Wiktionary, Creative Commons Attribution/Share-Alike License

From Latin virus ("poison, slime, venom").


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  • "By cunning, cautious; or by nature, cold, 15

    In maiden madness, virulently bold!"

    Sheridan, School for Scandal

    January 2, 2008

  • That's an excellent metaphoric use of virulent.

    January 4, 2008

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

    September 11, 2011