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

Has anything changed about getting the flu vaccine? —Mary Walrath-Holdridge, USA Today, 23 Oct. 2025

Weekly updates from the more specific FluView have stopped, as have summary reports from RESP-NET that tracks hospitalizations for Covid-19, flu and RSV from a network of hospitals across the country. —Deidre McPhillips, CNN Money, 22 Oct. 2025

While flu and other respiratory viruses circulate all year, cases tend to increase during fall and winter months in Wisconsin. —Anna Kleiber, jsonline.com, 22 Oct. 2025

The pill is a single-dose antiviral treatment for people ages 5 and above, typically taken within 48 hours of the onset of flu symptoms. —Annika Kim Constantino, CNBC, 16 Oct. 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