virus

noun
vi·​rus | \ ˈvī-rəs How to pronounce virus (audio) \
plural viruses

Definition of virus

1a : 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.
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Recent Examples on the Web Instead of going to a large congregate shelter or a hotel, Johnson boarded a bus with a plastic sheet partition protecting the driver from the virus. Los Angeles Times, "Could a San Francisco experiment be an answer to L.A.’s sprawling street encampments?," 7 May 2021 While younger people face lower risks of severe health outcomes from the virus, health officials have said the age of hospitalization has gotten younger as older age groups have been vaccinated at higher rates. Stephen Hudak, orlandosentinel.com, "Plenty of vaccines are available in Orlando, but people aren’t showing up," 7 May 2021 While the vaccine has been shown to prevent hospitalization and death -- which is excellent news -- some people can still get sick from the virus. Katia Hetter, CNN, "How should vaccinated parents navigate summer? A doctor's advice," 7 May 2021 Older Americans were hit hardest by COVID-19, with the largest percentage of deaths from the virus belonging to the over-65 cohort. Star Tribune, "Vaccinated vacationers: Baby boomers who got the jab first were ready to roll," 6 May 2021 For most of the pandemic, older Alaskans — whose age put them at a higher risk for severe illness from the virus — made up the largest share of the state’s hospitalizations. Annie Berman, Anchorage Daily News, "Fairbanks’ pandemic-high spike in COVID-19 patients pushes regional hospital to its limit," 6 May 2021 Usually, Covid-19 symptoms aren’t as severe for kids when compared to adults, but that doesn’t mean that kids feel no effect from the virus. Leah Rosenbaum, Forbes, "Why Experts Say It’s Vital That Parents Get Their Kids Vaccinated For Covid," 6 May 2021 And 34,070 vaccines started, bringing Ohio to 40.95% of its residents at least partially inoculated from the virus. cleveland, "Ohio reports 1,387 new coronavirus cases, 4 million Ohioans have completed vaccine: Thursday update," 6 May 2021 More than 577,000 Americans have died from the virus, and there were nearly 30,000 new cases on Monday, according to Johns Hopkins University. Stefan Becket, CBS News, "Biden sets goal of fully vaccinating 160 million adults by July 4," 5 May 2021

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'virus.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of virus

1599, in the meaning defined at sense 4

History and Etymology for virus

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.

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Last Updated

9 May 2021

Cite this Entry

“Virus.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/virus. Accessed 13 May. 2021.

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More Definitions for virus

virus

noun
vi·​rus | \ ˈvī-rəs How to pronounce virus (audio) \

Kids Definition of virus

1 : a disease-causing agent that is too tiny to be seen by the ordinary microscope, that may be a living organism or may be a very special kind of protein molecule, and that can only multiply when inside the cell of an organism
2 : a disease caused by a virus
3 : a usually hidden computer program that causes harm by making copies of itself and inserting them into other programs

virus

noun
vi·​rus | \ ˈvī-rəs How to pronounce virus (audio) \

Medical Definition of virus

1a : 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

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