virus

noun

vi·​rus ˈvī-rəs How to pronounce virus (audio)
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
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 prejudiceV. 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 At least 58 million birds were slaughtered last year to limit the spread of the virus. Marina Johnson, The Indianapolis Star, 5 Apr. 2024 That increases the environmental load of virus on occasion. Helen Branswell, STAT, 5 Apr. 2024 The infections came less than 24 hours after the Centers for Disease Control reported a person in Texas had been infected with the virus after coming into close contact with dairy cattle, just over a week after sick dairy cattle in Texas and Kansas tested positive for the virus. USA TODAY, 4 Apr. 2024 Human infections with bird flu viruses can happen when the virus gets into a person’s eyes, nose or mouth, or is inhaled. The Enquirer, 3 Apr. 2024 The virus, which is highly contagious among wild birds and poultry, has now spread to dairy farms, according to the U.S. Department of Agriculture. Patrick Jarenwattananon, NPR, 3 Apr. 2024 Cows in Idaho and Michigan have also tested positive for the virus. Dylan Sloan, Fortune, 3 Apr. 2024 The latter two are added to water at safe levels determined by the Environmental Protection Agency to kill parasites, bacteria, and viruses that could be harmful. Sophia Panych, Allure, 2 Apr. 2024 Although the two types of mosquitoes that transmit dengue are found in some counties, the virus is not endemic in the state, according to the Ohio Department of Health. Chad Murphy, The Enquirer, 27 Mar. 2024

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'virus.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

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 "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

Time Traveler
The first known use of virus was in 1599

Dictionary Entries Near virus

Cite this Entry

“Virus.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/virus. Accessed 12 Apr. 2024.

Kids Definition

virus

noun
vi·​rus ˈvī-rəs How to pronounce virus (audio)
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 How to pronounce virus (audio)
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
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
Last Updated: - Updated example sentences
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