virus

noun

vi·​rus ˈvī-rəs 

plural viruses

1

a

: any of a large group of submicroscopic infectious agents that are usually regarded as nonliving extremely complex molecules, that typically contain a protein coat surrounding an RNA or DNA core of genetic material but no semipermeable membrane, that are capable of growth and multiplication only in living cells, and that cause various important diseases in humans, animals, and plants

also : filterable virus

b

: a disease or illness caused by a virus

c

: the causative agent of an infectious disease

2

: something that poisons the mind or soul

the force of this virus of prejudice

—V. S. Waters

3

: a computer program that is usually disguised as an innocuous program or file, that often produces copies of itself and inserts them into other programs, and that when run usually performs a malicious action (such as destroying data or damaging software)

4

archaic : venom sense 1

Examples of virus in a Sentence

Is the illness caused by bacteria or a virus?

I think I have the virus that's going around this winter.

The software checks your hard drive for viruses.

Recent Examples on the Web

These levels help support the immune system and help fight off viruses like the flu and COVID-19. —Sarah Anzlovar, Ms, Verywell Health, 19 Apr. 2024

Back in April 2022, the United States reported its first human case of bird flu after an inmate at a Colorado prison contracted the virus after direct exposure to infected poultry. —Vanessa Etienne, Peoplemag, 18 Apr. 2024

Santos Rodriguez, 28, was diagnosed with H.I.V. in 2016 and has taken a daily pill ever since to suppress the virus. —Apoorva Mandavilli, New York Times, 17 Apr. 2024

Visas were denied to reduce the virus’ spread — and probably just because Trump didn’t like a lot of the immigrants. —George Skelton, Los Angeles Times, 15 Apr. 2024

Other birds can become infected through direct contact with the virus particles, or through contact with surfaces contaminated with viruses from infected birds. —Katia Hetter, CNN, 11 Apr. 2024

Officials attribute it to the drop in the U.S. vaccination rate for the deadly and preventable virus amid a global surge in cases. —Eduardo Cuevas, USA TODAY, 11 Apr. 2024

An adult from Wayne County who had traveled internationally and had no record of measles immunization had the virus in February. —Kristen Jordan Shamus, Detroit Free Press, 10 Apr. 2024

The worker has since recovered and didn’t pass the virus to anyone else, according to the CDC. —Natalie Wallington, Kansas City Star, 10 Apr. 2024

Word History

Etymology

Middle English, "pus, discharge from a sore, semen," borrowed from Latin vīrus (neuter) "venom, poisonous fluid, acrid element in a substance, secretion with medical or magical properties," going back to an Indo-European base *u̯is-/*u̯īs- "poison, venom," whence also Middle Irish fí "venom, poison, evil," Greek īós "poison," Tocharian A wäs and Tocharian B wase, Sanskrit viṣáṃ, Avestan viš, viša- (also vīš?); (sense 1) borrowed from German, borrowed from Latin

Note: The application of Latin vīrus to the submicroscopic infectious agents now considered viruses (rather than to any infectious agent) was apparently first made by the Dutch microbiologist Martinus Beijerinck (1851-1931) in "Ueber ein Contagium vivum fluidum als Ursache der Fleckenkrankheit der Tabaksblätter," Verhandelingen der Koninklijke Akademie van Wetenschappen te Amsterdam, Tweede Sectie, Deel VI, no. 5 (1898). Beijerinck, in studying tobacco mosaic virus, mistakenly believed that the agent was a fluid (contagium vivum fluidum, "living fluid infection") because it passed through filters capable of trapping bacteria. — The neuter gender of vīrus suggests that it was originally an s-stem; forms in text other than the nominative and accusative are perhaps found only in Lucretius. The length of the vowel in Latin, Irish, and Greek, in contrast to the short vowel in Tocharian and Indo-Iranian, has been variously accounted for. M. Mayrhofer (Etymologisches Wörterbuch des Altindoarischen) suggests that the etymon was originally a root noun, *u̯īs, *u̯is-ó-, with lengthening of the monosyllabic vowel; the daughter languages then generalized one or the other form.

First Known Use

1599, in the meaning defined at sense 4

Phrases Containing virus

• AIDS virus
• coxsackie virus
• delta virus
• DNA virus
• Ebola virus
• EB virus
• Epstein-Barr virus
• filterable virus
• hepatitis delta virus
• hepatitis D virus
• human immunodeficiency virus
• Marburg virus
• Norwalk virus
• parainfluenza virus
• polio virus
• Powassan virus
• Powassan virus disease
• respiratory syncytial virus
• RNA virus
• simian immunodeficiency virus
• slow virus
• tobacco mosaic virus
• vaccinia virus
• West Nile virus
• Zika virus

Kids Definition

virus

noun

vi·​rus ˈvī-rəs 

plural viruses

1

: any of a large group of very tiny infectious agents that are too small to be seen with the ordinary light microscope but can often be seen with the electron microscope, that are usually regarded as nonliving complex molecules, that have an outside coat of protein around a core of RNA or DNA, that can grow and multiply only in living cells, and that cause important diseases in plants and animals including human beings compare filterable virus

2

: a disease or illness caused by a virus

3

: a computer program that is usually hidden within another seemingly harmless program and that produces copies of itself and inserts them into other programs and usually performs a malicious action (as destroying data) compare trojan horse sense 2, worm sense 5

Etymology

from Latin virus "poison, venom, secretion"

Medical Definition

virus

noun

vi·​rus ˈvī-rəs 

1

a

: the causative agent of an infectious disease

b

: any of a large group of submicroscopic, infectious agents that are usually regarded as nonliving, extremely complex molecules or sometimes as very simple microorganisms, that typically contain a protein coat surrounding an RNA or DNA core of genetic material but no semipermeable membrane, that are capable of growth and multiplication only in living cells, and that cause various important diseases in humans, animals, and plants

also : filterable virus

c

: a disease caused by a virus

2

: an antigenic but not infectious material (as vaccine lymph) obtainable from a case of an infectious disease