alert

US /əˈlɝːt/
UK /əˈlɝːt/
"alert" picture
1.

a warning of danger or a problem

:
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The weather service issued a tornado alert.
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We received an alert about a possible security breach.
:
warningalarmsignalnotificationheads-up
1.

to warn someone of a danger, threat, or problem

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The system will alert you if there's any unusual activity.
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The sudden noise alerted the guard.
:
warnnotifyinformapprisesignal
1.

quick to notice any unusual and potentially dangerous or difficult circumstances; vigilant

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The guard remained alert throughout his shift.
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It's important to stay alert when driving long distances.
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vigilantwatchfulattentiveawareobservant
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spoiler alertseizure-alert dog