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English definition of “alert”

alert

adjective  /əˈlɜrt/ us  
quick to see, understand, and act in a particular situation: When you’re driving, you must stay alert. We had to be alert to any danger signs in the economy.

alert

noun [C/U]  /əˈlɜrt/ us  
a warning to people to get ready to deal with something dangerous: [U] The police were on the alert for (= watching carefully for) any sign of trouble.
alert
verb [T]  /əˈlɜrt/ us  
The auto company mailed letters to owners of that model car, alerting them of safety risks.
(Definition of alert from the Cambridge Academic Content Dictionary © Cambridge University Press)
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