noun, plural vi·rus·es.
an ultramicroscopic (20 to 300 nm 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.
Informal. a viral disease.
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.
Origin of virus
1590–1600;Related formsvi·rus·like, adjectivean·ti·vi·rus, adjective
< Latin vīrus
slime, poison; akin to ooze2
Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
Examples from the Web for virus
Contemporary Examples of virus
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.
The fact that the virus is still alive has sustained many safety concerns, both rational and irrational, about its use.
In some ways, the rapid spread of the virus there should not be surprising.
Craig Spencer, the New York doctor who contracted Ebola in Guinea, was declared “cured” of the virus last week.
Historical Examples of virus
Such an idea is as fatal to society as we know it as a virus plague.
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.
But what am I saying, A W, to you who are so free from the virus of culture?
British Dictionary definitions for virus
noun plural -ruses
Derived Formsvirus-like, adjective
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
Word Origin for virus
C16: from Latin: slime, poisonous liquid; related to Old English wāse marsh, Greek ios poison
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
Word Origin and History for virus
late 14c., "venomous substance," from Latin virus "poison, sap of plants, slimy liquid," probably from PIE root *weis- "to melt away, to flow," used of foul or malodorous fluids, with specialization in some languages to "poisonous fluid" (cf. Sanskrit visam "poison," visah "poisonous;" Avestan vish- "poison;" Latin viscum "sticky substance, birdlime;" Greek ios "poison," ixos "mistletoe, birdlime; Old Church Slavonic višnja "cherry;" Old Irish fi "poison;" Welsh gwy "fluid, water," gwyar "blood"). Main modern meaning "agent that causes infectious disease" first recorded 1728. The computer sense is from 1972.
Online Etymology Dictionary, © 2010 Douglas Harper
n. pl. vi•rus•es
Any of a large group of submicroscopic agents that act as parasites and consist of a segment of DNA or RNA surrounded by a coat of protein. Because viruses are unable to replicate without a host cell, they are not considered living organisms in conventional taxonomic systems. Nonetheless, they are described as live when they are capable of replicating and causing disease.
A disease caused by a virus.
The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
Related formsviral adjective
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.
The American Heritage® Science Dictionary
Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Microorganisms consisting of DNA and RNA molecules wrapped in a protective coating of proteins. Viruses are the most primitive form of life. They depend on other living cells for their reproduction and growth. (See under “Medicine and Health.”)
A minute organism that consists of a core of nucleic acid surrounded by protein. Viruses, which are so small that a special kind of microscope is needed to view them, can grow and reproduce only inside living cells. (See under “Life Sciences.”)
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.