warn

verb

ˈwȯrn 

warned; warning; warns

transitive verb

1

a

: to give notice to beforehand especially of danger or evil

b

: to give admonishing advice to : counsel

c

: to call to one's attention : inform

2

: to order to go or stay away

—often used with off

intransitive verb

: to give a warning

warner noun

Synonyms of warn

• alert
• advise

Examples of warn in a Sentence

I had been warned about the difficulties of the job.

She warned me that the stove was still hot.

“This won't be easy,” he warned.

Nobody warned me about the dangers.

I warned him to be careful, but he didn't listen to me.

She warned us not to go too close to the fire.

Recent Examples on the Web

The Financial Action Task Force, the global money-laundering watchdog, has warned that criminals exploit citizenship and residency programs to conceal their identities, launder illicit wealth and evade justice. — Arkansas Online, 3 Oct. 2026

In recent weeks, some leading AI firms have warned that their models’ coding abilities could foment humanity’s demise. — Shun Graves, Chicago Tribune, 2 Oct. 2026

The World Monuments Fund (WMF), an independent organization, has warned that funding constraints, intensifying climate change, and a lack of access to expertise are putting World Heritage Sites at extreme risk. — News Desk, Artforum, 2 Oct. 2026

Finchelstein, Stanley and others warn that the most dangerous moment for democracies can be when a wanna-be dictator loses momentum. — Los Angeles Times, 2 Oct. 2026

Word History

Etymology

Middle English warnen, going back to Old English wearnian, warnian "to be on one's guard, make aware, put on one's guard," going back to West Germanic *warnōjan- (whence Middle Dutch waernen "to provide with, give notice of a danger," Old High German warnōn), probably causative derivative of Germanic *wara- "cognizant, watchful" — more at ware entry 1

First Known Use

before the 12th century, in the meaning defined at transitive sense 1a

Phrases Containing warn

• I have to warn you
• pre-warn
• warn off

Rhymes for warn

• borne
• bourn
• bourne
• corn
• morn
• morne
• mourn
• porn
• scorn
• shorn
• sworn
• thorn

Kids Definition

warn

verb

ˈwȯ(ə)rn 

1

a

: to give notice to beforehand especially of danger or evil

b

: to give advice to : counsel

2

: to order to go or stay away

warned us off their land

warner noun