an ultramicroscopic (20 to 300 nanometers in diameter), metabolically inert, infectious agent that replicates only within the cells of living hosts, mainly bacteria, plants, and animals: composed of an RNA or DNA core, a protein coat, and, in more complex types, a surrounding envelope.
a viral disease: He stayed home sick with a virus for nearly two weeks.
a corrupting influence on morals or the intellect; poison.
a segment of self-replicating code planted illegally in a computer program, often to damage or shut down a system or network.
- vi·rus·like, adjective
- an·ti·vi·rus, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
How to use virus in a sentence
The vaccine is delivered through a “carrier virus” that causes a common cold in chimpanzees but does not affect humans.
He became delirious, his heartbeat grew ragged, his blood teemed with the virus, and his lungs, liver and kidneys began to fail.
By May 27, five people had succumbed to the virus and 16 more were infected.Jail Threats for Sierra Leone Ebola Victims’ Families | Abby Haglage | December 10, 2014 | THE DAILY BEAST
The current FDA-approved measles vaccine consists of live but weakened measles virus that is injected into the arm.Powdered Measles Vaccine Could Be Huge for Developing World | Kent Sepkowitz | December 2, 2014 | THE DAILY BEAST
The fact that the virus is still alive has sustained many safety concerns, both rational and irrational, about its use.Powdered Measles Vaccine Could Be Huge for Developing World | Kent Sepkowitz | December 2, 2014 | THE DAILY BEAST
If there is neuritis from the virus it becomes intense and causes muscular contractions, paresis, and paralysis.Essays In Pastoral Medicine | Austin Malley
(p. 442) But it was the more poisonous virus of Secession which finally laid their proud city low.The Boys of '61 | Charles Carleton Coffin.
The scientists of Sator knew that the virus was virulent; in fact, too virulent for its own good.
They knew that shortly after every Nansalian died, the virus, too, would be dead.
It killed the host every time, and the virus could not live outside a living cell.
British Dictionary definitions for virus
any of a group of submicroscopic entities consisting of a single nucleic acid chain surrounded by a protein coat and capable of replication only within the cells of living organisms: many are pathogenic
informal a disease caused by a virus
any corrupting or infecting influence
computing an unauthorized program that inserts itself into a computer system and then propagates itself to other computers via networks or disks; when activated it interferes with the operation of the computer
- virus-like, adjective
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Scientific definitions for virus
Any of various extremely small, often disease-causing agents consisting of a particle (the virion), containing a segment of RNA or DNA within a protein coat known as a capsid. Viruses are not technically considered living organisms because they are devoid of biological processes (such as metabolism and respiration) and cannot reproduce on their own but require a living cell (of a plant, animal, or bacterium) to make more viruses. Viruses reproduce first either by injecting their genetic material into the host cell or by fully entering the cell and shedding their protein coat. The genetic material may then be incorporated into the cell's own genome or remain in the cytoplasm. Eventually the viral genes instruct the cell to produce new viruses, which often cause the cell to die upon their exit. Rather than being primordial forms of life, viruses probably evolved from rogue pieces of cellular nucleic acids. The common cold, influenza, chickenpox, smallpox, measles, mumps, yellow fever, hemorrhagic fevers, and some cancers are among the diseases caused by viruses.
Computer Science A computer program that duplicates itself in a manner that is harmful to normal computer use. Most viruses work by attaching themselves to another program. The amount of damage varies; viruses may erase all data or do nothing but reproduce themselves.
- viral adjective
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Cultural definitions for virus (1 of 3)
See computer virus.
The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.