From Middle English virulent (“leaking or seeping pus, purulent; (of putrefaction) extremely severe (sense uncertain)”)[and other forms],^[1] borrowed from Latin vīrulentus (“poisonous”), from vīrus (“poison; venom; slime, slimy liquid; stinking smell; nasty taste”)^[2] (ultimately from Proto-Indo-European *wisós (“poison; slime; fluidity”)) + -ulentus (suffix meaning ‘abounding in, full of’, forming adjectives).

Sense 4 (“of a pathogen: replicating within its host cell, then immediately causing it to undergo lysis”) is derived from French virulent, which was first used in this sense by the French biologist François Jacob (1920–2013) and his co-authors in a 1953 article.^[2][3]

• (Received Pronunciation) IPA^(key): /ˈvɪɹ(j)ʊl(ə)nt/, /-ɹ(j)ə-/

• Audio (Southern England):

  (file)

• (General American) IPA^(key): /ˈvɪɹ(j)ələnt/
• Hyphenation: vi‧ru‧lent

virulent (comparative more virulent, superlative most virulent)

1. Of animals, plants, or substances: extremely venomous or poisonous.

   Antonyms: harmless, nonvirulent

2. (figurative) Extremely hostile or malicious; intensely acrimonious.

   The politicians were virulent in their hatred of the president.

   • c. 1515–1516, published 1568, John Skelton, Againſt venemous tongues enpoyſoned with ſclaunder and falſe detractions &c.:

     More venemous and much more virulent / Then any poyſoned tode, or any ſerpent.

   • 1963, Margery Allingham, “The Well House”, in The China Governess: A Mystery, London: Chatto & Windus, →OCLC, page 105:

     It was a casual sneer, obviously one of a long line. There was hatred behind it, but of a quiet, chronic type, nothing new or unduly virulent, and he was taken aback by the flicker of amazed incredulity that passed over the younger man's ravaged face.

   • 2025 December 15, Greg Sargent, Inside Stephen Miller’s Dark Plot to Build a MAGA Terror State‎^[1], The New Republic:

     They were targeted by a virulent strain of nativism toward those from Southern and Eastern Europe that was largely about race.

3. (medicine) Of a disease or disease-causing agent: malignant, able to cause damage to the host.

   Antonyms: benign, nonvirulent

4. (microbiology) Of a pathogen: replicating within its host cell, then immediately causing it to undergo lysis. [from 1953]

• virulence
• virulency (dated)
• virus

• pathogenic

• 👁 Image
  virulence on Wikipedia.Wikipedia

• evil turn

Borrowed from Latin vīrulentus.

• IPA^(key): (Central) [bi.ɾuˈlen]
• IPA^(key): (Balearic, Valencia) [vi.ɾuˈlent]

virulent (feminine virulenta, masculine plural virulents, feminine plural virulentes)

1. virulent

• virulentament

• virulència

• “virulent”, in Diccionari de la llengua catalana [Dictionary of the Catalan Language] (in Catalan), second edition, Institute of Catalan Studies [Catalan: Institut d'Estudis Catalans], April 2007
• “virulent”, in Gran Diccionari de la Llengua Catalana, Grup Enciclopèdia Catalana, 2026
• “virulent” in Diccionari normatiu valencià, Acadèmia Valenciana de la Llengua.
• “virulent” in Diccionari català-valencià-balear, Antoni Maria Alcover and Francesc de Borja Moll, 1962.

(This etymology is missing or incomplete. Please add to it, or discuss it at the Etymology scriptorium.)

virulent (plural and definite singular attributive virulente)

1. This term needs a translation to English. Please help out and add a translation, then remove the text {{rfdef}}.

• “virulent” in Den Danske Ordbog

Borrowed from Late Latin virulentus. The second sense is probably a semantic loan from English.

• IPA^(key): /vi.ʁy.lɑ̃/

virulent (feminine virulente, masculine plural virulents, feminine plural virulentes)

1. (medicine) virulent
2. virulent (hostile)

• virulemment

• virulence

• “virulent”, in Trésor de la langue française informatisé [Digitized Treasury of the French Language], 2012

Borrowed from Latin virulentus.

• IPA^(key): /viʁuˈlɛnt/
• Hyphenation: vi‧ru‧lent

• Audio (Germany (Berlin)):

  (file)

virulent (strong nominative masculine singular virulenter, not comparable)

1. (medicine)

• “virulent” in Digitales Wörterbuch der deutschen Sprache
• “virulent” in Uni Leipzig: Wortschatz-Lexikon
• “virulent” in Duden online

Borrowed from French virulent, from Latin virulentus.

virulent m or n (feminine singular virulentă, masculine plural virulenți, feminine/neuter plural virulente)

1. virulent