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

Oceania had been the world’s only region free of the deadly bird-flu strain until last month, when an infected seabird was discovered on a Western Australian beach. — Todd Symons, CNN Money, 22 July 2026

Other less common symptoms include vomiting, body aches, headache, a low-grade fever and other flu-like symptoms. — Mateo Rosiles, USA Today, 21 July 2026

This means that immunity against other threats such as the common cold, flu or coronavirus can disappear if a person contracts measles without any existing immunity. — Paul Sisson, San Diego Union-Tribune, 20 July 2026

Health officials urged anyone who lives, works or has visited the affected area since late June and develops flu-like symptoms to contact a health care provider immediately. — Brittany Miller , Stephen Sorace, FOXNews.com, 18 July 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