virulent

Etymology

PIE word *wisós From Middle English virulent (“leaking or seeping pus, purulent; (of putrefaction) extremely severe (sense uncertain)”) [and other forms], borrowed from Latin vīrulentus (“poisonous”), from vīrus (“poison; venom; slime, slimy liquid; stinking smell; nasty taste”) (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.

adj

1. Of animals, plants, or substances: extremely venomous or poisonous.
2. (figurative) Extremely hostile or malicious; intensely acrimonious.
   The politicians were virulent in their hatred of the president.
   More venemous and much more virulent / Then any poyſoned tode, or any ſerpent. c. 1515–1516, published 1568, John Skelton, Againſt venemous tongues enpoyſoned with ſclaunder and falſe detractions &c.
3. (medicine) Of a disease or disease-causing agent: malignant, able to cause damage to the host.
4. (microbiology) Of a pathogen: replicating within its host cell, then immediately causing it to undergo lysis.