virus
noun
vi·rus
| \ ˈvī-rəs
\
\
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)
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 disease is caused by a virus and is spread by midges, small biting insects. — Paul A. Smith, Milwaukee Journal Sentinel, "A midge-borne disease has killed hundreds of deer in Iowa but so far Wisconsin hasn't been hit as hard," 11 Sep. 2019 An average of 80 people per week are sickened by the virus, which has infected most people in Congo’s North Kivu province. — Time, "Congolese Girl, 9, Dies After Testing Positive for Ebola in Uganda," 30 Aug. 2019 An average of 80 people per week are sickened by the virus, which has infected most people in Congo's North Kivu province. — NBC News, "Girl with Ebola entering Uganda from Congo," 30 Aug. 2019 It was later determined that it was probably caused by a virus. — Jenni Balck As Told To Carolyn L. Todd, SELF, "My Child Can’t Get Vaccinated. Here’s What Life Is Like for Us.," 26 Aug. 2019 The continent's last case of polio caused by the wild virus was detected on 21 August 2016 in Nigeria. — Bukola Adebayo, CNN, "Africa begins countdown to being polio free as Nigeria marks 3 years without disease," 21 Aug. 2019 Hepatitis A is a liver infection that is contagious and caused by a virus. — Katrina Pross, Twin Cities, "Minnesota homeless, drug users hit by hepatitis A outbreak, health department says," 8 Aug. 2019 Mr Burnashev’s previous film, about a zombie apocalypse triggered by a virus released from melting permafrost, had a budget of just 3.4m roubles ($53,000). — The Economist, "The pitfalls of making movies in Siberia," 11 July 2019 Now, a new study reveals that most childhood pneumonia—some 60% of global cases—is caused by viruses. — Alex Fox, Science | AAAS, "Viruses—not bacteria—cause most childhood pneumonia," 27 June 2019These 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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More Definitions for virus
virus
noun
vi·rus
| \ ˈvī-rəs
\
\
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
\
\
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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