warn
Americanverb (used with object)
-
warns,
present (3rd person singular)
-
warned,
past participle, past
-
warning
present participle
-
to give notice, advice, or intimation to (a person, group, etc.) of danger, impending evil, possible harm, or anything else unfavorable.
They warned him of a plot against him. She was warned that her life was in danger.
- Synonyms:
- forewarn
-
to urge or advise to be careful; caution.
to warn a careless driver.
-
to admonish or exhort, as to action or conduct.
She warned her employees to be on time.
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to notify, advise, or inform.
to warn a person of an intended visit.
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to give notice to (a person, group, etc.) to go, keep at a distance, etc. (often followed by away, off, etc.).
A sign warns trespassers off the grounds. A marker warned boats away from the dock.
-
to give authoritative or formal notice to (someone); order; summon.
to warn a person to appear in court.
verb (used without object)
-
warns,
present (3rd person singular)
-
warned,
past participle, past
-
warning
present participle
verb
-
to notify or make (someone) aware of danger, harm, etc
-
(tr; often takes a negative and an infinitive) to advise or admonish (someone) as to action, conduct, etc
I warn you not to do that again
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(takes a clause as object or an infinitive) to inform (someone) in advance
he warned them that he would arrive late
-
(tr; usually foll by away, off, etc) to give notice to go away, be off, etc
he warned the trespassers off his ground
Synonym Usage
Warn, caution, admonish imply attempting to prevent another from running into danger or getting into unpleasant or undesirable circumstances. To warn is to speak plainly and usually in strong terms: to warn him about danger and possible penalties. To caution is to advise about necessary precautions, to put one on one's guard about possibly harmful circumstances or conditions, thus emphasizing avoidance of undesirable consequences: to caution him against driving in such weather. Admonish suggests giving earnest, authoritative advice with only tacit references to danger or penalty: to admonish a person for neglecting his duties.
Other Word Forms
Derived Forms
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warnernoun
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prewarnverb (used with object)
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rewarnverb (used with object)
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unwarnedadjective
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well-warnedadjective
Inflected Forms
Participles
Conjugated Forms
Present
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warnsimple
-
warnssimple
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have warnedperfect
-
has warnedperfect
-
am warningprogressive
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are warningprogressive
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is warningprogressive
-
have been warningperfect progressive
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has been warningperfect progressive
Past
-
warnedsimple
-
had warnedperfect
-
was warningprogressive
-
were warningprogressive
-
had been warningperfect progressive
Future
Etymology
Origin of warn
First recorded before 1000; Middle English warnen, Old English warnian; cognate with German warnen; Cf. ware 2
Explanation
When you warn someone, you advise them to be careful or tell them about a problem or danger. If you perform a dangerous stunt, you should probably warn your audience, "Don't try this at home." Many traffic signs are meant to warn drivers about hazards, like bridges that get slippery in the rain or bumps in the road. And the purpose of a dog's growl is to warn another dog (or human) that it's stressed or fearful. A warning is a helpful message, no matter what form it comes in, and to warn is to send this message. The Old English root is warnian, "give notice of impending danger."
Vocabulary lists containing warn
"The Secret Water"
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"The Black Ferris" by Ray Bradbury
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Tasting the Sky
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
See Examples For:
Clashes between family members in business can lead to tensions that sever a personal relationship, experts warn.
From The Wall Street Journal ● Oct. 17, 2026
Mothers who married men with children used to warn me to run screaming from step situations.
From The Wall Street Journal ● Oct. 14, 2026
He used an annual speech at the domestic intelligence service's headquarters in London to also warn of rising threats from Iran and "extreme right-wing terrorism".
From BBC ● Oct. 13, 2026
Still, consumer advocates warn that introducing probabilistic rewards into daily retail purchases normalizes speculative risk in everyday life.
From MarketWatch ● Oct. 13, 2026
How do you warn an entire country that something terrible is about to happen?
From "The First State of Being" by Erin Entrada Kelly
The government is urging people to save water as it warns action is needed to prevent severe drought conditions becoming "the new normal".
From BBC ● Oct. 16, 2026
OpenAI instructs employees to avoid wearing company logos outside the office and warns them of espionage risks like honeypots.
From The Wall Street Journal ● Oct. 15, 2026
Spartan Chemical warns that inappropriate exposure can cause the types of effects detainees experienced.
From Los Angeles Times ● Oct. 8, 2026
The securities industry is generating record tax revenue for New York, increasing the city’s and state’s vulnerability to a downturn, the state comptroller warns.
From Barron's ● Oct. 6, 2026
“Don’t let that boy fall,” Abuela warns me.
From "Merci Suárez Changes Gears" by Meg Medina
Cornell President Michael Kotlikoff warned in a recent faculty town hall meeting that pushing social events into private houses beyond the school’s purview—“into the shadows”—could exacerbate problems.
From The Wall Street Journal ● Oct. 18, 2026
"If we become too dependent on services or products from a given country, that makes us vulnerable, whatever that country may be," Skjold-Lorange warned.
From Barron's ● Oct. 17, 2026
Southern California Edison warned about possible shutoff of electricity because of the wind.
From Los Angeles Times ● Oct. 16, 2026
Signatories said Birmingham had been central to the show's identity since it began and warned that separating cast and production teams could affect the way the programme is made.
From BBC ● Oct. 16, 2026
Dad’s warned me not to ask too many questions.
From "Code Name Kingfisher" by Liz Kessler
Silver’s decline “syncs up with the warning lights we are seeing in the energy markets — with persistently high energy prices virtually certain to slow the economy, or worse,” Gleason told MarketWatch.
From MarketWatch ● Oct. 17, 2026
The weather authority said fire danger would remain through much of the day Saturday, warning residents to be prepared for emergency evacuations.
From Barron's ● Oct. 17, 2026
And knowing this tool can be restricted without any warning or consultation has sparked major concern in Ukraine.
From BBC ● Oct. 16, 2026
In particular, fire officials drew heat for failing to pre-deploy engines to Pacific Palisades, despite forecasters warning of extreme fire weather conditions.
From Los Angeles Times ● Oct. 16, 2026
My attempt to think of Viola instead of the warning posters fails.
From "The Bletchley Riddle" by Ruta Sepetys and Steve Sheinkin
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Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
