flu

noun

ˈflü 

1

: influenza

2

: any of several virus diseases marked especially by respiratory or intestinal symptoms

flu-like

ˈflü-ˌlīk 

adjective

Examples of flu in a Sentence

He came down with a bad bout of the flu.

Recent Examples on the Web

Walsh was out of the fold on this night, band leader Don Henley explained to the crowd, due to his coming down with the flu. —Jim Harrington, Mercury News, 25 Jan. 2026

That would seem to include the WHO group that assesses what flu strains are circulating and makes critical decisions about updating flu shots. —Mike Stobbe, Arkansas Online, 24 Jan. 2026

Bass-Sulpizio, who was slowed during the week with the flu, grabbed eight rebounds. —Don Norcross, San Diego Union-Tribune, 24 Jan. 2026

The avian flu virus has no vaccine, and experts consulted by the city and others interviewed by the Orlando Sentinel say the best practice is to allow the disease to run its course, with the thought that surviving birds would develop immunity. —Ryan Gillespie, The Orlando Sentinel, 24 Jan. 2026

Word History

Etymology

by shortening

First Known Use

1839, in the meaning defined at sense 1

Phrases Containing flu

• anti-flu
• Asian flu
• avian flu
• bird flu
• blue flu
• flu season
• swine flu
• yuppie flu

Rhymes for flu

• blew
• blue
• boo
• brew
• chew
• chou
• clue
• coo
• coup
• crew
• cue
• dew

Kids Definition

flu

noun

ˈflü 

1

: influenza sense 1

2

: any of several virus diseases that are something like a cold

flu-like

ˈflü-ˌlīk

adjective

Medical Definition

flu

noun

ˈflü 

1

: influenza

2

: any of several chiefly viral illnesses marked especially by respiratory or gastrointestinal symptoms see intestinal flu

flu-like

-ˌlīk 

adjective

also flulike

flu-like symptoms