[ uh-lurt ]
/ əˈlɜrt /
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See synonyms for: alert / alerted / alerts / alertly on Thesaurus.com

fully aware and attentive; wide-awake; keen: She had an alert mind.
swift; agile; nimble.
verb (used with object)
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Idioms about alert

    on the alert, on guard against danger; in readiness; vigilant: The state police are on the alert for an escaped convict believed to be in the area.

Origin of alert

First recorded in 1590–1600; 1940–45 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

synonym study for alert

1. 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.


a·lert·ly, adverba·lert·ness, nounhy·per·a·lert, adjectiveun·a·lert·ed, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023


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.

Where does alert come from?

The first records of alert come from around the 1600s. It comes from the Italian all’erta, meaning “on the watch, on the lookout.”

Another type of alert is the notifications we get on our mobile phones, computers, and similar devices. These alerts aren’t meant to warn you but to notify you. For example, a sound might play when you receive a voice call, an icon might appear on the screen when you receive a new email, or a light might blink when you receive a new text message. All of these are alerts that alert you to new activity in an application. To keep from being overwhelmed with alerts, some people shut off some or all alerts on their devices.

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What are some other forms related to alert?

  • alertly (adverb)
  • alertness (noun)
  • hyperalert (adjective)
  • unalerted (adjective)

What are some synonyms for alert?

What are some words that share a root or word element with alert

  • alertly
  • alertness
  • unalerted

What are some words that often get used in discussing alert?

How is alert used in real life?

Alert is most commonly used to refer to notifications on mobile phones and other digital devices.


Try using alert!

Is alert used correctly in the following sentence?

I shut off all the alerts on my phone when I go to sleep at night.

How to use alert in a sentence

British Dictionary definitions for alert

/ (əˈlɜːt) /

adjective (usually postpositive)
vigilantly attentivealert to the problems
brisk, nimble, or lively
verb (tr)
to warn or signal (troops, police, etc) to prepare for action
to warn of danger, an attack, etc

Derived forms of alert

alertly, adverbalertness, noun

Word Origin for alert

C17: from Italian all'erta on the watch, from erta lookout post, from ergere to build up, from Latin ērigere; see erect
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Other Idioms and Phrases with alert


see on the alert.

The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.