flu
Americannoun
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a specific variety of influenza, usually named for its point of dissemination or its animal vector.
Hong Kong flu; swine flu.
noun
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short for influenza
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any of various viral infections, esp a respiratory or intestinal infection
Etymology
Origin of flu
First recorded in 1830–40; shortened form
Compare meaning
How does flu compare to similar and commonly confused words? Explore the most common comparisons:
Explanation
The flu is a disease that's easily spread between people. When you have body aches, a fever, and a sore throat, you probably have the flu. The word flu is shorthand for "influenza," the official name of this infectious, viral illness. It's not unusual to get the flu, especially in the winter, and while it usually isn't serious, it can be deadly for some groups of people. Your chances of getting the flu are greatly reduced if you get a flu shot. The Italian root influenza means "influenza" or "epidemic," but also "visitation" or "influence of the stars."
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
Avian flu, cost-cutting and Brexit are among the reasons behind the transfer of captive birds from one of Northern Ireland's best-known wildlife sites, according to the charity that runs it.
From BBC ● Oct. 17, 2026
If you missed this whole saga, it began with the flu.
From Slate ● Oct. 16, 2026
The California Department of Fish and Wildlife announced Wednesday that Jackie died from highly pathogenic avian influenza, also known as bird flu.
From Los Angeles Times ● Oct. 15, 2026
"I had the flu," Talarico told the news network.
From Barron's ● Oct. 12, 2026
Lying in one place for this long is for bedtime or getting over the flu.
From "Shouting at the Rain" by Lynda Mullaly Hunt
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Get a wordDefinitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
