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

The flu and food poisoning led him to withdraw from the Nedback Golf Challenge in South Africa to end his 2009 season as a 20-year-old on the European Tour. —Edgar Thompson, The Orlando Sentinel, 7 Mar. 2026

Lowe’s rehab was also interrupted by the flu, which kept him from the ballpark for a few days. —Jeff Fletcher, Oc Register, 6 Mar. 2026

Last month his department had opted not to review an application for a new mRNA flu vaccine from pharmaceutical company Moderna. —Youri Benadjaoud, ABC News, 6 Mar. 2026

The agency initially refused to review Moderna’s flu shot before reversing course. —Angelica Peebles, CNBC, 6 Mar. 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
• stomach flu
• 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