Definition of virus
1a : any of a large group of submicroscopic infective 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 virusb : a disease or illness caused by a virusc : 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 hidden within another seemingly innocuous program and that produces copies of itself and inserts them into other programs and usually performs a malicious action (such as destroying data)
4 archaic : venom 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 of virus from the Web
Some viruses replicate themselves by inserting their DNA into the genomes of their hosts.
Now some of them are raising children affected by the virus.
Most of those affected were infected with hepatitis C. Of the 1,200 people infected with the HIV virus, fewer than 250 still are alive, according to the Hemophilia Society.
The easy one, at least in theory, is hepatitis C, a liver-damaging virus frequently contracted by injection-drug users that can cause cirrhosis and cancer.
Firms including Russia's anti-virus Kaspersky Lab, said clues in the code indicate that the program's authors would have been incapable of decrypting the data, further evidence that the ransom demands were a smoke screen.
Animal specialists are warning pet owners to beware of a highly contagious virus that has killed at least three dogs in the Louisville area.
But in 1985, after South African forces raided Gaborone, destroying buildings and killing civilians, Mr. Masire was forced to eject the A.N.C. Another challenge in the 1980s was the rapid spread of the virus that causes AIDS.
The origins of the virus were still unknown early Wednesday.
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.
Origin and Etymology of virus
Latin, venom, poisonous emanation; akin to Greek ios poison, Sanskrit viṣa; in senses 1 & 3, from New Latin, from Latin
First Known Use: 1599See Words from the same year
VIRUS Defined for Kids
Definition of virus for Students
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
Medical Definition of virus
1a: the causative agent of an infectious diseaseb: any of a large group of submicroscopic, infective 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 virusc: a disease caused by a virus
2: an antigenic but not infective material (as vaccine lymph) obtainable from a case of an infectious disease
Seen and Heard
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