alert
Americanadjective
noun
-
an attitude of vigilance, readiness, or caution, as before an expected attack.
-
a warning or alarm of an impending military attack, a storm, etc..
We'd just boarded the bus when the alert sounded.
-
the period during which such a warning or alarm is in effect.
verb (used with object)
-
to warn (troops, ships, etc.) to prepare for action.
-
to warn of an impending raid, attack, storm, etc..
The radio alerted coastal residents to prepare for the hurricane.
-
to advise or warn; cause to be on guard.
to alert gardeners to the dangers of some pesticides.
idioms
adjective
-
vigilantly attentive
alert to the problems
-
brisk, nimble, or lively
noun
-
an alarm or warning, esp a siren warning of an air raid
-
the period during which such a warning remains in effect
-
-
on guard against danger, attack, etc
-
watchful; ready
on the alert for any errors
-
verb
-
to warn or signal (troops, police, etc) to prepare for action
-
to warn of danger, an attack, etc
Usage
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.
Related Words
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.
Other Word Forms
Etymology
Origin of alert
First recorded in 1590–1600; 1940–45 alert 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
Explanation
Alert! Alert! Alert! Did I get your attention? When you are alert, you are awake and ready. When you issue an alert you give warning, alerting people to, or notifying them of, a concern. Alert is one of the rare words that can be used in the same form as a noun, verb, and adjective. In all parts of speech, alert implies preparedness. The word is derived from the French a l'erte which translates to "on the watch." When you hear the word, imagine an alarm going off. The alarm is the alert. When you hear it, you have been alerted and you are now alert.
Vocabulary lists containing alert
The Best Starting Words for Wordle
Looking to grow your vocabulary? Check out this interactive, curated word list from our team of English language specialists at Vocabulary.com – one of over 17,000 lists we've built to help learners worldwide!
Common Five-letter Words for Wordle, List 3
Interested in learning more words like this one? Our team at Vocabulary.com has got you covered! You can review flashcards, quiz yourself, practice spelling, and more – and it's all completely free to use!
List 2
Want to remember this word for good? Start your learning journey today with our library of interactive, themed word lists built by the experts at Vocabulary.com – we'll help you make the most of your study time!
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
The chart comes from Fernando Martín of Global Trade Alert, who dug into the contrasting strategies in a recent report.
From The Wall Street Journal • Feb. 5, 2026
You get Surfshark Search, a private search engine with no ads or tracking, Surfshark Alert for data breach monitoring, and Alternative ID for generating fake personal details for online registrations.
From Salon • Dec. 10, 2025
These arrests have sparked the creation of a new messaging system called "Black Alert" to spread word quickly through ultra-Orthodox communities and summon protesters to prevent arrests taking place.
From BBC • Dec. 3, 2025
The Long Beach-based activist runs the Stop ICE Raids Alert Network, which sends out text alerts with the locations of raids to more than half a million people nationwide.
From Los Angeles Times • Nov. 25, 2025
If you let the Amber Alert people tell it, Scoob’s in danger no matter where he is right now.
From "Clean Getaway" by Nic Stone
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
