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[in-floo-en-zuh] /ˌɪn fluˈɛn zə/
Pathology. an acute, commonly epidemic disease, occurring in several forms, caused by numerous rapidly mutating viral strains and characterized by respiratory symptoms and general prostration.
Compare flu.
Veterinary Pathology. an acute, contagious disease occurring in horses and swine, characterized by fever, depression, and catarrhal inflammations of the eyes, nasal passages, and bronchi, and caused by a virus.
Origin of influenza
1735-45; < Italian < Medieval Latin influentia influence
Related forms
influenzal, adjective
influenzalike, adjective
postinfluenzal, adjective Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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Examples from the Web for influenza
Contemporary Examples
Historical Examples
  • The lucky alarm of an influenza decided what might not have been decided quite so soon.

    Lady Susan Jane Austen
  • "Measles—or influenza," he said, with a pursing of the lips.

    Nell, of Shorne Mills

    Charles Garvice
  • The result is colds, pneumonia, influenza—eventually tuberculosis.

    The World in Chains John Mavrogordato
  • I was told you had influenza, or cold: but I suppose that is all over by this time.

    Letters of Edward FitzGerald Edward FitzGerald
  • When Jones has the influenza, Brown dutifully catches cold in the head.

    The Jest Book Mark Lemon
British Dictionary definitions for influenza


a highly contagious and often epidemic viral disease characterized by fever, prostration, muscular aches and pains, and inflammation of the respiratory passages Also called grippe, (informal) flu
Derived Forms
influenzal, adjective
Word Origin
C18: from Italian, literally: influence, hence, incursion, epidemic (first applied to influenza in 1743)
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 influenza

1743, borrowed during an outbreak of the disease in Europe, from Italian influenza "influenza, epidemic," originally "visitation, influence (of the stars)," from Medieval Latin influentia (see influence). Used in Italian for diseases since at least 1504 (cf. influenza di febbre scarlattina "scarlet fever") on notion of astral or occult influence. The 1743 outbreak began in Italy. Often applied since mid-19c. to severe colds.

Online Etymology Dictionary, © 2010 Douglas Harper
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influenza in Medicine

influenza in·flu·en·za (ĭn'flōō-ěn'zə)
An acute contagious viral infection, commonly occurring in epidemics or pandemics, and characterized by inflammation of the respiratory tract and by the sudden onset, fever, chills, muscular pain, headache, and severe prostration. Also called grippe.

in'flu·en'zal adj.
The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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influenza in Science
A highly contagious infectious disease that is caused by any of various viruses of the family Orthomyxoviridae and is characterized by fever, respiratory symptoms, fatigue, and muscle pain. It commonly occurs in epidemics, one of which killed 20 million people between 1917 and 1919.

Our Living Language  : Since ancient times, influenza has periodically swept the world. Until recently, people could not tell how this illness, which we call the flu, could spread so widely. Before people knew that organisms cause disease, they thought the stars influenced the spread of influenza. Influenza comes ultimately from the Latin word influentia, meaning "influence of the stars." Today, however, the stars are no longer blamed for the flu. Inhaling influenza viruses causes the spread of the illness.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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influenza in Culture
influenza [(in-flooh-en-zuh)]

Commonly called the flu; an acute and infectious disease of the respiratory system caused by a virus and characterized by fever, muscle pain, headache, and inflammation of the mucous membranes in the respiratory tract.

The 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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