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virus

[vahy-ruh s] /ˈvaɪ rəs/
noun, plural viruses.
1.
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.
2.
Informal. a viral disease.
3.
a corrupting influence on morals or the intellect; poison.
4.
a segment of self-replicating code planted illegally in a computer program, often to damage or shut down a system or network.
Origin
1590-1600
1590-1600; < Latin vīrus slime, poison; akin to ooze2
Related forms
viruslike, adjective
antivirus, adjective
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
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Examples from the web for viruses
  • There are many mosaic viruses, each afflicting a different plant.
  • It is in the viruses' best interest to let the host survive, but accidents happen.
  • Over the years many other cancer viruses have been discovered in animals.
  • What was once the stuff of science fiction, the recipe for creating deadly viruses, is now a frighteningly real possibility.
  • viruses play an important role in many ear infections, and can set the scene for a bacterial infection.
  • Dengue fever is caused by one of four different but related viruses.
  • Arthropod-borne viruses causing fever and rash syndromes.
  • The test tubes in which the viruses are cultured contain penicillin to prevent bacterial spoilage.
  • Except that his quarry is viruses, not butterflies and birds.
  • At the moment it takes months to produce new vaccines, which is too slow to respond to fast-mutating viruses.
British Dictionary definitions for viruses

virus

/ˈvaɪrəs/
noun (pl) -ruses
1.
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
2.
(informal) a disease caused by a virus
3.
any corrupting or infecting influence
4.
(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
Derived Forms
virus-like, adjective
Word Origin
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
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Word Origin and History for viruses

virus

n.

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
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viruses in Medicine

virus vi·rus (vī'rəs)
n. pl. vi·rus·es

  1. Any of various simple submicroscopic parasites of plants, animals, and bacteria that often cause disease and that consist essentially of a core of RNA or DNA surrounded by a protein coat. Unable to replicate without a host cell, viruses are typically not considered living organisms.

  2. 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.
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viruses in Science
virus
  (vī'rəs)   
Plural viruses
  1. 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.

  2. 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 © 2002. Published by Houghton Mifflin. All rights reserved.
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viruses in Culture
virus [(veye-ruhs)]

plur. viruses

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.”)

Note: Viruses cause many diseases. (See viral infection.)
virus [(veye-ruhs)]

plur. viruses

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.”)

virus definition


See computer virus.

The American Heritage® New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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viruses in Technology
The Free On-line Dictionary of Computing, © Denis Howe 2010 http://foldoc.org
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