alert
Americanadjective
noun
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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)
-
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
-
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
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are alertingprogressive
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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:
In Newport Beach, police posted an alert online Saturday saying ongoing flooding had closed all city beaches and piers until further notice.
From Los Angeles Times ● Oct. 10, 2026
As soon as he showed his passport at check-in at the resort, the local carabinieri got an automatic alert.
From BBC ● Oct. 10, 2026
"When we hear an air‑raid alert, I pray to God -- and to our air defence, because the life of our city depends on them," he said.
From Barron's ● Oct. 8, 2026
A soldier received an air-raid alert for ballistic missiles.
From The Wall Street Journal ● Oct. 6, 2026
“There was a Butterfly alert not five minutes ago, I just got the alert . . .” Her words trailed off as she looked at us, taking in our dripping-wet pajamas and dirt-smudged faces.
From "Glitch" by Laura Martin
Their earliest soft X-ray emission has been far more difficult to observe because most narrow-field X-ray telescopes depend on gamma-ray alerts to locate a burst before turning toward it.
From Science Daily ● Oct. 8, 2026
She is among an increasing number of Ukrainian passengers facing disruption and long delays, as air raid alerts trigger emergency evacuations far from the battlegrounds of the east.
From BBC ● Oct. 6, 2026
At the Yeezy beauty salon in downtown Kyiv, no clients have canceled their appointments today, despite five air-raid alerts so far.
From The Wall Street Journal ● Oct. 4, 2026
As The Times first reported in January 2025, west Altadena evacuation alerts came “as the fire approached and, in some cases, after it had already begun impacting the area,” the report found.
From Los Angeles Times ● Oct. 2, 2026
Think of the colon as a traffic cop that alerts you about road conditions up ahead.
From "Woe Is I" by Patricia T. O'Conner
At the raid last month at my own university, police were alerted by an anonymous tip.
From The Wall Street Journal ● Oct. 9, 2026
Anthropic has previously alerted police departments to more substantive information about potential risks.
From The Wall Street Journal ● Oct. 9, 2026
A major incident was declared and dozens of homes were evacuated after police were alerted to three suspicious vehicles near the airbase in the early hours of 27 September.
From BBC ● Oct. 8, 2026
True to his mission, Kenig got behind the steering wheel and raced towards the Gaza border in the early hours of October 7, 2023 after a colleague alerted him to what was happening.
From Barron's ● Oct. 5, 2026
The asthma was under control, but the doctor alerted me to something else—Malia’s body mass index, a measure of health that factors together height, weight, and age, was beginning to creep up.
From "Becoming" by Michelle Obama
For Lapointe, alerting scientists to the crater has become an unforgettable experience.
From Science Daily ● Sep. 22, 2026
It adds that in "none of these cases did the agent actually pursue alerting humans at all".
From BBC ● Sep. 9, 2026
Far-right activist Laura Loomer, who has feuded publicly with Yiannopoulos, celebrated his detention and claimed credit for alerting federal authorities to his immigration status in multiple posts on X.
From Salon ● Aug. 29, 2026
Question: “Do you recall alerting him to that heightened sensitivity?”
From The Wall Street Journal ● Aug. 27, 2026
The magic woven into his skin was alerting him.
From "The Way to Rio Luna" by Zoraida Cordova
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.
