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

As its name suggests, this gastrointestinal infection typically causes plenty of diarrhea and loose stools, alongside abdominal cramps and flu-like symptoms such as fever and malaise. —Julia Ries Wexler, SELF, 26 Dec. 2025

Taking zinc may help alleviate symptoms, including fever, in respiratory infections such as colds and the flu. —Carrie Madormo, Verywell Health, 26 Dec. 2025

Boo Boo Sick Song More than just the discomfort of getting sick, kids seem to feel distressed by all the new and unfamiliar feelings in their body caused by something like the flu or a cold. —Elisabeth Sherman, Parents, 26 Dec. 2025

The others — for respiratory syncytial virus (RSV), rotavirus, flu and chickenpox — do not. —Aria Bendix, NBC news, 26 Dec. 2025

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
• 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