Virulence

Part of speech: noun

Pronunciation: /ˈvɪɹjələns/

Definitions

1. The capacity of a pathogen or harmful agent to produce severe disease or death in a host organism
2. The degree to which a disease-causing microorganism or toxin can damage tissues and cause serious illness or mortality
3. The extent to which a microorganism or toxin can cause severe illness or death in a host

Etymology: Virulence began as a word for poison. Its root is Latin "virus," which meant a slimy liquid, a poison or venom, and the same Latin root gave us "virulentus," meaning full of poison. Latin "virulentia" carried that sense of venomous potency into Middle French as "virulence," and English borrowed the term from there. The Latin "virus" that gave the root its bite is also the source of the modern word for infectious agents, which is a reminder of how closely the idea of poison and infection were once tied together. Across its history, the word has moved from describing literal toxicity in a substance to describing how aggressively a disease-causing agent can harm the body. Its modern medical sense, applied to microbes and toxins, reflects the same underlying notion: the measure of how much harm something is capable of doing.

Synonyms: toxicity, malignancy

Antonyms: harmlessness, gentleness