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 new vaccine’s mRNA technology, the same platform as Moderna’s COVID shots, provides about 27% more coverage against influenza than traditional flu vaccines, according to a study of 40,000 adults ages 50-64. — Cindy Krischer Goodman, Miami Herald, 15 Sep. 2026

The health department is urging anyone who lives in the Bronx community cluster or has visited the area since August and is experiencing flu-like symptoms to seek medical attention immediately. — Elijah Westbrook, CBS News, 15 Sep. 2026

Who shouldn't get a flu vaccine Although a flu vaccine is recommended for most, there are some individuals for which a flu vaccine may not be recommended. — Yi-Jin Yu, ABC News, 15 Sep. 2026

The effort developed from previous years when health professionals brought COVID-19 vaccines and later flu shots to the festival. — J.m. Banks, Kansas City Star, 14 Sep. 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