influenza

noun

in·​flu·​en·​za ˌin-(ˌ)flü-ˈen-zə How to pronounce influenza (audio)
1
a
: 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."

influenzal adjective
influenzal pneumonia
influenzal symptoms

Examples of influenza in a Sentence

Recent Examples on the Web Health officials yesterday announced a new policy focused on actions people can take to reduce the spread of a variety of common respiratory viruses, including COVID, but also influenza, RSV, and more. Taylor Wilson, USA TODAY, 4 Mar. 2024 However, Covid-19 is not like RSV or influenza, particularly given the long-term organ damage caused by the SARS2-CoV virus. Judy Stone, Forbes, 1 Mar. 2024 Much of the data the CDC had tracked on COVID-19 alongside other trends, like influenza and RSV, will also continue to be published. Alexander Tin, CBS News, 1 Mar. 2024 The study included more than 81,000 people hospitalized with COVID-19 between 2020 and 2022 and nearly 11,000 with seasonal influenza between 2015 and 2019. Claire Bugos, Verywell Health, 27 Feb. 2024 The California Department of Public Health said the change was to better align the state’s guidance with that for other respiratory illnesses such as RSV and influenza. Harriet Blair Rowan, The Mercury News, 19 Feb. 2024 Though mentioned in passing in the Oxford anthology, the actual story of Hemingway’s intertwining of war and influenza is complicated and revealing. Adam Gopnik, The New Yorker, 19 Feb. 2024 Diseases like measles, influenza, and tuberculosis were common. Kira Caspers, The Arizona Republic, 14 Feb. 2024 During one week last month, more than 82,000 people who visited an emergency department were diagnosed with influenza — an 8% bump compared to the prior week, according to the CDC. Alexandra Banner, CNN, 7 Feb. 2024

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'influenza.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

Etymology

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

First Known Use

1743, in the meaning defined at sense 1a

Time Traveler
The first known use of influenza was in 1743

Dictionary Entries Near influenza

Cite this Entry

“Influenza.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/influenza. Accessed 18 Mar. 2024.

Kids Definition

influenza

noun
in·​flu·​en·​za ˌin-(ˌ)flü-ˈen-zə How to pronounce influenza (audio)
1
: a very contagious virus disease with fever, exhaustion, severe aches and pains, and inflammation of the respiratory tract
2
: any of various diseases of human beings or domestic animals that are usually caused by viruses and are typically marked by fever and respiratory symptoms
Etymology

from Italian influenza, literally "influence," from Latin influentia "influence," derived from earlier influere "to flow in," from in- "in, into" and fluere "to flow"

Word Origin
Originally the Italian word influenza meant what the similar-sounding word in English, influence, means: "the act or power of producing an effect indirectly." But it also had the Latin meaning of "an invisible fluid through which the stars and planets control and direct the earth and things and people on it." When epidemics raged through Europe, no one knew what the real cause was. People blamed them on evil stars working through the invisible fluid, or influence. For this reason the Italians called the disease influenza. In 1743 an epidemic very much like our modern flu began in Rome and spread. That was when the Italian word was borrowed into English. Flu is a shortened form of influenza.

Medical Definition

influenza

noun
in·​flu·​en·​za ˌin-(ˌ)flü-ˈen-zə How to pronounce influenza (audio)
1
a
: 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."

influenzal adjective
influenzal pneumonia
influenzal symptoms

More from Merriam-Webster on influenza

Last Updated: - Updated example sentences
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