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.
A small group of these nurses were eventually allowed to treat Black soldiers in the US Army struck down by Spanish flu.
From Barron's ● Nov. 1, 2026
In early October, for example, Talarico took a brief hiatus from the campaign trail to recover from a severe case of the flu.
From Salon ● Oct. 31, 2026
It would take federal authorities deciding to update this season’s flu shots for Moderna to roll out a newer vaccine later this year.
From The Wall Street Journal ● Oct. 30, 2026
This mutation clearly emerged after drugmakers updated seasonal vaccines, so existing shots appear to be partially mismatched to this year’s flu, Bloom said.
From The Wall Street Journal ● Oct. 30, 2026
With Mami down with the flu, Abuela has been busy cooking dinner for us every night.
From "Merci Suárez Changes Gears" by Meg Medina
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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.
