Definition of alert in English:


Syllabification: a·lert
Pronunciation: /əˈlərt



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  • 1The state of being watchful for possible danger: security forces were placed on alert
    More example sentences
    • The main north-south highway was reopened on Thursday but motorists were urged to remain on alert against possible dangers caused by the continuing heavy rains.
    • And now, as his execution by lethal injection nears, some clinics providing abortions are on alert for possible violence.
    • But the industry was put on alert about the possible tax rises at a conference this month when a representative from the Revenue said the memoranda would need to be reviewed.
  • 1.1An announcement or signal warning of danger: a bomb alert an alert sounded and all the fighters took off
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    • A flood alert was sounded in Kinnaur, Shimla, Kulu and Mandi districts last evening after water started overflowing from the lake, bringing along a lot of silt.
    • The all-clear had in fact sounded from an initial alert when the bomb was dropped.
    • The Environment Agency issued flood alerts for several rivers and part of the A12 was sealed off.
    warning, notification, notice; siren, alarm, signal, danger signal, distress signal
  • 1.2A period of vigilance in response to a warning of danger: traffic was halted during the alert
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    • The country is on a war alert following terrorist attacks on its Parliament building.
    • The incident follows a similar alert at a post office earlier this week.
    • Thousands of holidaymakers who lost luggage following the airport security alert earlier this month are unlikely to be able to claim compensation from their insurers, it emerged last week.


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  • Warn (someone) of a danger, threat, or problem, typically with the intention of having it avoided or dealt with: he alerted people to the dangers of smoking police were alerted after three men drove away without paying
    More example sentences
    • Wenger did the game a service by alerting us to the dangers.
    • Surely it would make more sense to put up an advert outside a football ground alerting men to the dangers of testicular or prostate cancer?
    • A pensioner is lucky to be alive after her dog alerted her to the danger of a fire at her home
    warn, notify, apprise, forewarn, put on one's guard, put on the qui vive
    informal tip off, clue in


on the alert

Vigilant and prepared: the security forces must be on the alert for an upsurge in violence
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  • The terrorist decides where and when he will strike, while the security forces must constantly be on the alert.
  • The committee appeals to everyone to exercise more vigilance and to be on the alert at all times, particularly in the run-up to Christmas.
  • To avoid overlooking opportunities, we must forever be on the alert.



More example sentences
  • Both Aaron and Ryan moved carefully and alertly, and Ryan had his sword drawn.
  • An original thinker always alertly attuned to contemporary culture, he was admired for his intellectual style and the felicity with which he expressed his ideas in his many books and articles.
  • Thankfully, however, the deer do wise up quickly, alertly scanning their surroundings for different sounds or a hint of movement that wasn't there the day before.


late 16th century (originally in military use): from French alerte, from Italian all' erta 'to the watchtower'.

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