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 cause was classified as norovirus, a contagious virus that causes nausea, vomiting and diarrhea, and is commonly known as the stomach flu. —Miami Herald, 3 Oct. 2025

But Terk, in Texas, told me that about 70 percent of his practice’s supply of flu shots contained the compound, which prevents contamination in multidose vials. —Katherine J. Wu, The Atlantic, 3 Oct. 2025

About one in six parents reported delaying or skipping vaccines (excluding seasonal flu and COVID-19), often citing safety concerns or distrust. —Suhail Bhat, USA Today, 2 Oct. 2025

Veterans in Northwest Arkansas and the River Valley have several walk-in flu vaccination options through the Veterans Health Care System of the Ozarks this flu season. —Arkansas Online, 2 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