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[vir-yuh-luh nt, vir-uh-] /ˈvɪr yə lənt, ˈvɪr ə-/
actively poisonous; intensely noxious:
a virulent insect bite.
Medicine/Medical. highly infective; malignant or deadly.
Bacteriology. causing clinical symptoms.
violently or spitefully hostile.
intensely bitter, spiteful, or malicious:
a virulent attack.
Origin of virulent
1350-1400; Middle English verulent < Latin vīrulentus, equivalent to vīr(us) poison (see virus) + -ulentus -ulent
Related forms
virulently, adverb
hypervirulent, adjective
hypervirulently, adverb
nonvirulent, adjective
nonvirulently, adverb
supervirulent, adjective
supervirulently, adverb
unvirulent, adjective
unvirulently, adverb
Can be confused
violent, virulent.
1. venomous. 5. vicious, acerbic.
1. harmless. Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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Examples from the Web for virulent
Contemporary Examples
Historical Examples
  • The shade resting on the valley appeared that of a mighty, virulent hand.

    The Strollers Frederic S. Isham
  • Duplicates, first buying of, 16—most virulent form of bibliomania, 173.

    The Book-Hunter

    John Hill Burton
  • The scientists of Sator knew that the virus was virulent; in fact, too virulent for its own good.

    Islands of Space John W Campbell
  • As soon as he was out of place, he had again been virulent in opposition.

  • Chicken-pox will become so virulent as to be mistaken for smallpox.

    Preventable Diseases Woods Hutchinson
British Dictionary definitions for virulent


  1. (of a microorganism) extremely infective
  2. (of a disease) having a rapid course and violent effect
extremely poisonous, injurious, etc
extremely bitter, hostile, etc
Derived Forms
virulently, adverb
Word Origin
C14: from Latin vīrulentus full of poison, from vīrus poison; see virus
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for virulent

c.1400, in reference to wounds, ulcers, etc., "full of corrupt or poisonous matter," from Latin virulentus "poisonous," from virus "poison" (see virus). Figurative sense of "violent, spiteful" is attested from c.1600. Related: Virulently.

Online Etymology Dictionary, © 2010 Douglas Harper
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virulent in Medicine

virulent vir·u·lent (vēr'yə-lənt, vēr'ə-)

  1. Extremely infectious, malignant, or poisonous. Used of a disease or toxin.

  2. Capable of causing disease by breaking down protective mechanisms of the host. Used of a pathogen.

  3. Intensely irritating, obnoxious, or harsh.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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