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

The story revolves around a young girl named Amy Bellafonte (Saniyya Sidney) after she is chosen to be a test subject for Project NOAH, a secret medical facility where scientists are experimenting with a dangerous virus. Kayla Keegan, Good Housekeeping, "Here’s How to Watch ‘The Passage,’ the New Fox Show Everyone’s Talking About," 21 Jan. 2019 Tap or click here to learn if your phone or tablet has a virus. Kim Komando, Fox News, "Streaming football, delete searches and more: Tech Q&A," 16 Sep. 2018 They were tested every six to 12 months to see if the infected partner still had the virus under control, and whether the other partner had caught it. Marilynn Marchione, The Seattle Times, "AIDS drugs show more promise for preventing new infections," 24 July 2018 It was officially declared an Ebola outbreak on May 8, when lab testing done in Kinshasa, Congo’s capital, confirmed that two patient samples had the virus. New York Times, "Ebola Outbreak in Central Africa Is ‘Largely Contained’," 28 June 2018 Last week, an Ohio man who has the hepatitis C virus was sentenced to 18 months in prison for spitting at Cleveland police and medics. Michelle Andrews, Washington Post, "If You’ve Got Hep C, Spitting Can Be A Felony," 19 June 2018 The symptoms of hepatitis A usually don't surface until the patient has had the virus for a few weeks, and not everyone shows symptoms. Julie Washington, cleveland.com, "Hepatitis A cases spike in Ohio; at-risk people urged to get vaccinated," 26 Apr. 2018 Lab tests indicated Brothers had herpes simplex virus, but the health department did not report the results to her. Staff And Wire Reports, Sun-Sentinel.com, "Parents of South Florida boy shot and killed at school 20 years ago get settlement from state," 27 Mar. 2018 In south and east Africa close on 20m people have the virus, almost four times more than in west and central Africa. The Economist, "Senegal’s successHow a small African nation is beating AIDS," 1 Mar. 2018

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

Latin, venom, poisonous emanation; akin to Greek ios poison, Sanskrit viṣa; in senses 1 & 3, from New Latin, from Latin

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Statistics for virus

Last Updated

11 May 2019

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Time Traveler for virus

The first known use of virus was in 1599

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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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More from Merriam-Webster on virus

Rhyming Dictionary: Words that rhyme with virus

Spanish Central: Translation of virus

Nglish: Translation of virus for Spanish Speakers

Britannica English: Translation of virus for Arabic Speakers

Britannica.com: Encyclopedia article about virus

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