Meaning of ALERT in English

ALERT

I. a ‧ lert 1 /əˈlɜːt $ -ɜːrt/ BrE AmE adjective

[ Date: 1500-1600 ; Language: French ; Origin: alerte , from Italian all' erta 'on the watch' ]

1 . giving all your attention to what is happening, being said etc:

The animal raised its head, suddenly alert.

Taking notes is one of the best ways to stay alert in lectures.

2 . able to think quickly and clearly:

Jack was as mentally alert as a man half his age.

3 . be alert to something to know about or understand something, especially a possible danger or problem:

The authorities should have been alert to the possibility of invasion.

—alertness noun [uncountable]

II. alert 2 BrE AmE verb [transitive]

1 . to officially warn someone about a problem or danger so that they are ready to deal with it:

The school immediately alerted the police.

2 . to make someone realize something important or dangerous

alert somebody to something

campaigns to alert the public to the dangers of HIV

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THESAURUS

▪ warn to tell someone about something bad or dangerous that might happen, so that they can avoid it or prevent it:

I warned you about sitting out in the sun too long.

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We were warned that there could be delays on the motorway, so we took another route.

▪ give somebody a warning to tell someone that if they continue to behave in an unsatisfactory way, they will be punished:

He’s already been given several warnings about handing in his essays late.

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The US gave a warning that if the hostages were not released, it would be forced to take military action.

▪ alert to officially or publicly warn people of possible danger so that they can prevent it or be ready to deal with it:

a campaign to alert people to the dangers of smoking

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An anonymous caller alerted the police that a bomb was due to go off.

▪ tip somebody off informal to secretly warn someone about something that is going to happen – used especially about warning the police about a crime:

The police found the drugs after being tipped off by local residents.

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Informants tipped the FBI off.

▪ caution formal to warn someone to do or not to do something in order to avoid a dangerous or bad result:

People are being cautioned against using credit cards abroad, in case of fraud.

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Health officials have cautioned the public to wash fruit thoroughly before eating it.

▪ forewarn /fɔːˈwɔːn $ fɔːrˈwɔːrn/ [usually passive] formal to warn someone about something that is going to happen, so that you are expecting it or ready for it:

We had been forewarned that the roads weren’t very good.

III. alert 3 BrE AmE noun

1 . [countable] a warning to be ready for possible danger

a bomb/fire/terrorist etc alert

a full-scale flood alert

The bomb alert was raised soon after midnight.

⇨ ↑ red alert

2 . on (the) alert (for something/somebody) ready to notice and deal with a situation or problem:

Be on the alert for anyone acting suspiciously.

Troops in the vicinity were put on alert.

on full alert (also on high alert) (=completely ready to deal with a dangerous situation)

All our border points are on full alert.

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THESAURUS

▪ warning something that you say or do to tell people about danger, or to tell them not to do something:

All cigarette packets carry a government health warning.

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She ignored her parents' warnings.

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The army issued a warning that anyone who was out on the streets after dark was likely to be shot.

▪ caution formal an official warning or a piece of advice telling you to be careful:

Caution: do not install electrical equipment near or around water sources.

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The video begins with a caution that you must do some warm-up exercises first.

▪ tip-off informal a warning that someone is about to do something, especially one given to the police about a crime:

Police were called to the hotel after a tip-off.

▪ alert a warning to be ready for possible danger that may happen soon:

Twelve flood alerts have been issued to areas along the River Severn.

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a fire alert

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The ambulance services were on red alert (=they were ready to take action immediately) .

▪ advisory formal an official warning or notice that gives information about a dangerous situation:

The air pollution gets so bad on some days that health advisories are posted at park entrances.

▪ caveat formal a warning that something may not be completely true, effective etc. Also used when pointing out that it is important to remember something:

The woman was offered treatment, but with the caveat that it had only a 30% chance of success.

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One caveat is that you must take the goods back to the shop within 14 days.

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There is one important caveat to this argument.

Longman Dictionary of Contemporary English.      Longman - Словарь современного английского языка.