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 Eagles played their first concert without Joe Walsh in 51 years in January when the guitarist was taken down by the flu. —Joseph Hudak, Rolling Stone, 21 Mar. 2026

Consider the company’s latest flu vaccine. —Bloomberg Opinion, Twin Cities, 20 Mar. 2026

The decision halted an order by Kennedy -- announced in January -- to end broad recommendations for all children to be vaccinated against flu, rotavirus, hepatitis A, hepatitis B, some forms of meningitis and RSV. —Arkansas Online, 17 Mar. 2026

The decision stops sweeping changes to childhood vaccine recommendations the federal government made in January, including no longer advising all children be vaccinated against the flu, rotavirus, hepatitis A, hepatitis B, some forms of meningitis and RSV. —Lisa Schencker, Chicago Tribune, 17 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