influenza

noun
in·​flu·​en·​za | \ˌin-(ˌ)flü-ˈen-zə \

Definition of influenza 

1a : an acute, highly contagious, respiratory disease caused by any of three orthomyxoviruses:

(1) or influenza A : moderate to severe influenza that in humans is marked especially by sudden onset, fever, sore throat, fatigue, muscle aches, inflammation of the respiratory mucous membranes, and cough, that has numerous variants caused by subtypes (such as H1N1, H2N2, or H3N2) of an orthomyxovirus (species Influenza A virus of the genus Influenzavirus A) infecting humans and various animals (such as birds or pigs), and that may occur in seasonal epidemics or sometimes pandemics following mutation in the causative virus

(2) or influenza B : influenza with less severe symptoms that is caused by an orthomyxovirus (species Influenza B virus of the genus Influenzavirus B) infecting only humans and especially children and that may occur in seasonal epidemics but not pandemics

(3) or influenza C : mild influenza that is often asymptomatic, is caused by an orthomyxovirus (species Influenza C virus of the genus Influenzavirus C) infecting only humans, and does not occur in epidemics or pandemics

b : any of various human respiratory infections of undetermined cause not used technically

2 : any of various virus diseases of domestic animals marked especially by fever, respiratory symptoms, and inflammation of mucous membranes

Note: All types of influenza are commonly called "the flu."

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Other Words from influenza

influenzal \ ˌin-​(ˌ)flü-​ˈen-​zəl \ adjective
influenzal pneumonia influenzal symptoms

Examples of influenza in a Sentence

Recent Examples on the Web

Disease-causing organisms can mutate; the influenza virus and HIV being notorious examples. William F. Bynum, WSJ, "‘Between Hope and Fear’ Review: Anxieties Immune to Reason," 16 Aug. 2018 Seasons often start with a higher proportion of influenza A cases, which tend to cause more serious illness. Stacey Burling, Philly.com, "As Delaware reports 3 more flu deaths, officials warn the season isn't over yet," 9 Apr. 2018 The virus hitting people left and right this year was a strain of influenza A, specifically the H3N2 strain. Kate Morgan, The Cut, "What to Know About Influenza B, the ‘Second Wave’ of Flu Season," 4 Apr. 2018 The process of creating the new vaccine starts by studying flu cases from this year and figuring out why this year’s vaccine wasn’t as effective with influenza A—this year’s deadliest strain—as the previous year’s. Emily Price, Fortune, "FDA is Already Working on Next Year's Flu Vaccine," 27 Feb. 2018 This year's epidemic has been caused by more garden variety forms, but the dominant strain, influenza A H3N2, has proven more resistant to the vaccine than others. Andy Marso, kansascity, "The CDC says flu season has peaked nationally. But guess where it's still rising. | The Kansas City Star," 26 Feb. 2018 Actual data won’t be available for months, although in Australia, the shot was only 10 percent effective against the influenza A H3N2 strain (New England Journal of Medicine, Nov. 29, 2017). Joe, The Seattle Times, "Will a flu shot make the flu less severe?," 18 Feb. 2018 As of the end of March, the CDC listed New Jersey and Pennsylvania as having low levels of influenza-like illness and Delaware as having minimal levels. Stacey Burling, Philly.com, "As Delaware reports 3 more flu deaths, officials warn the season isn't over yet," 9 Apr. 2018 Doctors like having a variety of drugs on hand for any disease, but especially influenza, which mutates quickly and which can develop resistance to drugs. NBC News, "New, fast-acting flu drug gets priority FDA review," 26 June 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'influenza.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of influenza

1743, in the meaning defined at sense 1a

History and Etymology for influenza

Italian, literally, influence, from Medieval Latin influentia; from the belief that epidemics were due to the influence of the stars

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Dictionary Entries near influenza

influencive

influent

influential

influenza

influx

influxion

info

Statistics for influenza

Last Updated

17 Nov 2018

Look-up Popularity

Time Traveler for influenza

The first known use of influenza was in 1743

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More Definitions for influenza

influenza

noun

English Language Learners Definition of influenza

medical : a common illness that is caused by a virus and that causes fever, weakness, severe aches and pains, and breathing problems

influenza

noun
in·​flu·​en·​za | \ˌin-flü-ˈen-zə \

Kids Definition of influenza

: a very contagious virus disease like a severe cold with fever

influenza

noun
in·​flu·​en·​za | \ˌin-(ˌ)flü-ˈen-zə \

Medical Definition of influenza 

1a : an acute, highly contagious, respiratory disease caused by any of three orthomyxoviruses:

(1) or influenza A : moderate to severe influenza that in humans is marked especially by sudden onset, fever, sore throat, fatigue, muscle aches, inflammation of the respiratory mucous membranes, and cough, is caused by any of several subtypes (such as H1N1, H2N2, or H3N2) of an orthomyxovirus (species Influenza A virus of the genus Influenzavirus A) infecting humans and various animals (such as birds or pigs), and may occur in seasonal epidemics or sometimes pandemics following mutation of the causative virus — see asian flu, avian influenza, bird flu, hong kong flu, spanish flu, swine flu, swine influenza

(2) or influenza B : influenza with less severe symptoms that is caused by an orthomyxovirus (species Influenza B virus of the genus Influenzavirus B) infecting only humans and especially children and that may occur in seasonal epidemics but not pandemics

(3) or influenza C : mild influenza that is often asymptomatic, is caused by an orthomyxovirus (species Influenza C virus of the genus Influenzavirus C) infecting only humans, and does not occur in epidemics or pandemics

b : any human respiratory infection of undetermined cause not used technically

2 : any of various viral diseases of domestic animals (as shipping fever of horses) marked especially by fever, respiratory symptoms, and inflammation of mucous membranes

Note: All types of influenza are commonly called “the flu.”

Other Words from influenza

influenzal \ -​zəl \ adjective
influenzal pneumonia influenzal symptoms

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More from Merriam-Webster on influenza

Spanish Central: Translation of influenza

Nglish: Translation of influenza for Spanish Speakers

Britannica English: Translation of influenza for Arabic Speakers

Britannica.com: Encyclopedia article about influenza

Comments on influenza

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