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

This year, the entire team caught the flu at an event in Puerto Rico. —Mark Zeigler, San Diego Union-Tribune, 26 May 2025

Bird flu appeared in the Bay Area in the winter of 2022 and 2023. —Ethan Baron, Mercury News, 24 May 2025

For years, federal health officials have told most Americans to expect annual updates to COVID-19 vaccines, similar to the annual flu shot. —Matthew Perrone, Los Angeles Times, 20 May 2025

Cases after Lightning in a Bottle festival Diagnosing Valley fever is tricky, mostly because its symptoms overlap with other respiratory illnesses including flu, Covid and pneumonia. —Kaitlin Sullivan, NBC news, 20 May 2025

Word History

Etymology

by shortening

First Known Use

1839, in the meaning defined at sense 1

Phrases Containing flu

• anti-flu
• Asian 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