virulence

noun

vir·​u·​lence ˈvir-ə-lən(t)s  ˈvir-yə- 

: the quality or state of being virulent: such as

a

: extreme bitterness or malevolence : rancor

the virulence of their hatred

She said the rising virulence of the rhetoric against Muslims has flooded her with sadness, grief, alienation and fear.

—Laura DaSilva

But the virulence of the campaign, on both sides … provides a clue to the deeper forces at work: the polarizing of politics in a traditionally moderate place.

—The Economist

b

: the relative capacity of a pathogen (such as a bacterium or virus) to overcome a host's defenses and cause disease or damage : the degree of pathogenicity of a causative agent of disease

a bacterial strain of low virulence

the virulence of a novel virus

also : the ability to overcome a host's defenses and cause disease or damage : the state of being pathogenic

With its newly acquired virulence, this otherwise mild-mannered avian influenza virus went wild.

—Rick Weiss

c

: relative severity or malignancy

Breast cancer is as diverse as the breast itself, appearing in many different guises. Some cancers seem to erupt out of ordinary breast issue with an awesome virulence, spreading rapidly throughout the body.

—David Plotkin

Synonyms

• severity
• bitterness
• hostility
• corrosiveness
• malice
• bile
• virulency

Examples of virulence in a Sentence

I was surprised by the virulence of the criticism.

Recent Examples on the Web

While VUMs require more testing to establish their true risks to public health, VOIs are explicitly confirmed to have genetic changes that affect virus characteristics like transmissibility and virulence. —Jack Knudson, Discover Magazine, 9 June 2025

The results revealed that pla depletion decreases the virulence and increases the length of plague infections in mice. —Sam Walters, Discover Magazine, 31 May 2025

The diminished virulence that the pathogen evolved in response to more of its hosts dying potentially caused these earlier plague pandemics to fizzle out. —Laura Baisas, Popular Science, 29 May 2025

The scale score measures the virulence of cancerous cells and tissues in the body, with a higher score meaning the cancer is more likely to spread quickly, as Biden’s has already done. —Dave Goldiner, New York Daily News, 19 May 2025

Word History

Etymology

borrowed from French & Latin; borrowed from French, going back to Middle French, borrowed from Late Latin vīrulentia "poisonous odor, infection," from Latin vīrulentus "full of poison, venomous" + -ia -ia entry 1 — more at virulent

First Known Use

1597, in the meaning defined above

Phrases Containing virulence

• hyper-virulence

Kids Definition

virulence

noun

vir·​u·​lence ˈvir-(y)ə-lən(t)s 

: the quality or state of being virulent

Medical Definition

virulence

noun

vir·​u·​lence ˈvir-(y)ə-lən(t)s 

: the quality or state of being virulent: as

a

: the relative capacity of a pathogen (as a bacterium or virus) to overcome a host's defenses and cause disease or damage : the degree of pathogenicity of a causative agent of disease

a bacterial strain of low virulence

attempted to determine the virulence of the newly identified virus

also : the ability to overcome a host's defenses and cause disease or damage : the state of being pathogenic

With its newly acquired virulence, this otherwise mild-mannered avian influenza virus went wild.

—Rick Weiss

b

: relative severity or malignancy

ameliorate the virulence of a disease