alert
Americanadjective
noun
-
alerts
plural
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an attitude of vigilance, readiness, or caution, as before an expected attack.
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a warning or alarm of an impending military attack, a storm, etc..
We'd just boarded the bus when the alert sounded.
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the period during which such a warning or alarm is in effect.
verb (used with object)
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alerts,
present (3rd person singular)
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alerted,
past participle, past
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alerting
present participle
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to warn (troops, ships, etc.) to prepare for action.
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to warn of an impending raid, attack, storm, etc..
The radio alerted coastal residents to prepare for the hurricane.
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to advise or warn; cause to be on guard.
to alert gardeners to the dangers of some pesticides.
idioms
adjective
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vigilantly attentive
alert to the problems
-
brisk, nimble, or lively
noun
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an alarm or warning, esp a siren warning of an air raid
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the period during which such a warning remains in effect
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-
on guard against danger, attack, etc
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watchful; ready
on the alert for any errors
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verb
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to warn or signal (troops, police, etc) to prepare for action
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to warn of danger, an attack, etc
Usage
What does alert mean? An alert is a warning or alarm, especially an alarm about dangerous weather or a military attack, as in The National Weather Service has alerts for tornadoes, hurricanes, Nor’easters, and other severe weather occurrences. Alert is also an attitude of readiness or caution, as in Tina was on alert for news of her son’s acceptance into college. Alert describes being fully attentive or wide awake, as in Sabine needs to be awake for several hours before she is alert and ready to work. You can be alert to the people and objects surrounding you. When you are alert, you’re ready to act or react instead of being surprised. But you can also be alert to concepts, ideas, and trends, ready to react to a change in others’ thoughts or to a change in the market. To alert means to advise or to warn, as with an alert. For example, your teacher might alert you that your big project is due soon, while a police department might alert the public about a dangerous person on the streets. Example: Alert the security team of the incident and then head home.
Synonym Usage
Alert, vigilant, watchful imply a wide-awake attitude, as of someone keenly aware of their surroundings. Alert describes a ready and prompt attentiveness together with a quick intelligence: The tourist was alert and eager to see the sights. Vigilant suggests some immediate necessity for keen, active observation, and for continuing alertness: Knowing the danger, the scout was unceasingly vigilant. Watchful suggests carefulness and preparedness: A stakeout requires watchful waiting.
Other Word Forms
Derived Forms
Inflected Forms
Nouns
Participles
Conjugated Forms
Present
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alertsimple
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alertssimple
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have alertedperfect
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has alertedperfect
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am alertingprogressive
-
are alertingprogressive
-
is alertingprogressive
-
have been alertingperfect progressive
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has been alertingperfect progressive
Past
-
alertedsimple
-
had alertedperfect
-
was alertingprogressive
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were alertingprogressive
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had been alertingperfect progressive
Future
Etymology
Origin of alert
First recorded in 1590–1600; 1940–45 alert for def. 4; from Italian all'erta, equivalent to all ( a ) “to, on the” + erta “lookout, watchtower,” originally feminine of erto, past participle of ergere from Latin ērigere to erect
Explanation
Alert! Alert! Alert! Did I get your attention? When you are alert, you are awake and ready. When you issue an alert you give warning, alerting people to, or notifying them of, a concern. Alert is one of the rare words that can be used in the same form as a noun, verb, and adjective. In all parts of speech, alert implies preparedness. The word is derived from the French a l'erte which translates to "on the watch." When you hear the word, imagine an alarm going off. The alarm is the alert. When you hear it, you have been alerted and you are now alert.
Vocabulary lists containing alert
The Best Starting Words for Wordle
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Common Five-letter Words for Wordle, List 3
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List 2
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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:
Instead, the programs frequently alert companies before inspectors show up.
From Los Angeles Times ● Oct. 9, 2026
But cyber security experts have warned users to change passwords as a precaution and be on alert for suspicious activity.
From BBC ● Oct. 8, 2026
If a voter sees federal agents at polling places in a manner that may be illegal, Diaz said, they should alert their local election officials.
From Salon ● Oct. 8, 2026
In a sign of the near-constant threat the city now faces, an air raid alert rang out as Klitschko was speaking to AFP.
From Barron's ● Oct. 8, 2026
With the new clothes they could not afford now rumpled and covered with grit, the bedraggled Babushkinovs and their quiet but unusually alert governess arrived in Saint Petersburg at last.
From "The Long-Lost Home" by Maryrose Wood
After receiving the onboard alerts from EP, Li quickly began the initial analysis.
From Science Daily ● Oct. 8, 2026
"ChatGPT for Teens could give parents false confidence in guardrails and safety alerts that frequently don't work," Tom Siegel, who leads the Youth AI Safety Institute within Common Sense, said.
From BBC ● Oct. 7, 2026
The report says ChatGPT failed tests tied to three requirements of California’s Adam’s Law: crisis referrals, parental alerts and age assurance.
From Los Angeles Times ● Oct. 7, 2026
During the many air-raid alerts, Iryna Stebnivska stays in the ward where her four-month-old baby is being treated, rather than going to the shelter.
From The Wall Street Journal ● Oct. 4, 2026
A pleasant ding echoes around the suite, and a light near my bed’s headrest alerts me to an incoming call.
From "Warcross" by Marie Lu
At the raid last month at my own university, police were alerted by an anonymous tip.
From The Wall Street Journal ● Oct. 9, 2026
The company alerted the department on October 7, and the two sides met the following day.
From Barron's ● Oct. 9, 2026
She said someone who went fishing in the swamp alerted the nearby naval base and people in the town about the crash.
From Barron's ● Oct. 5, 2026
US media reported a new threat led to the bombers being removed, which follows a major incident on 27 September when police were alerted to three "suspicious vehicles" near the airbase.
From BBC ● Oct. 5, 2026
A flash of light illuminates them both for an instant, and then every player is alerted that our Artifact is now in Hammie’s hands.
From "Warcross" by Marie Lu
For Lapointe, alerting scientists to the crater has become an unforgettable experience.
From Science Daily ● Sep. 22, 2026
At the moment I get the call alerting me that the deed is done, that Wiatt is officially settled out, I’m driving down Rodeo Drive.
From The Wall Street Journal ● Sep. 15, 2026
It adds that in "none of these cases did the agent actually pursue alerting humans at all".
From BBC ● Sep. 9, 2026
Its products also recently started recognizing designated people and alerting the homeowner.
From The Wall Street Journal ● Aug. 21, 2026
“I’m surprised you got to the front door without my gate guards alerting me,” the executive said, as nonchalant as could be.
From "Scythe" by Neal Shusterman
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
