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

Example Sentences

Recent Examples on the Web The groups that suffered most during the H1N1 influenza pandemic of 2009 were the same ones that took the brunt of COVID, a decade later. Ed Yong, The Atlantic, 30 Sep. 2022 The overall influenza vaccination rates among adults was 49.4% during the 2021-22 flu season when the season ended in June — up significantly from the 2010-2011 season when the vaccination rate was 40.5%. Helena Oliviero, ajc, 18 Oct. 2022 In the first half of 2020, then-Prime Minister Shinzo Abe repeatedly touted Avigan, earlier studied as an influenza treatment, as one of Japan’s best hopes for tackling Covid-19. Miho Inada, WSJ, 14 Oct. 2022 Avian influenza is an airborne respiratory virus that spreads among chickens via nasal and eye secretions and manure. Cristina Larue, Arkansas Online, 8 Oct. 2022 Canine influenza is a highly contagious viral infection that can cause your dog to get sick, materials from Bond Vet explain. Anna Kaufman, USA TODAY, 6 Oct. 2022 The best time to get the vaccine is before the flu begins spreading in your community, said Alicia Fry, who leads the influenza epidemiology and prevention team at the CDC. Abraham Gutman, Chicago Tribune, 4 Oct. 2022 Pfizer and its partner BioNTech are recruiting 25,000 healthy U.S. adults to receive either its experimental influenza shot or a regular kind, to see how effective the new approach proves this flu season. Lauran Neergaard, Anchorage Daily News, 3 Oct. 2022 Still, the influenza B/Yamagata lineage remains missing, according to a study published this week in the journal Eurosurveillance. Beth Mole, Ars Technica, 30 Sep. 2022 See More

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.

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 27 Nov. 2022.

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

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
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!


Odd Habits and Quirks

  • image1926873504
  • Which of the following best describes an easily irritated person?
Spell It

Hear a word and type it out. How many can you get right?

TAKE THE QUIZ
Universal Daily Crossword

A daily challenge for crossword fanatics.

TAKE THE QUIZ