\ ə-ˈlərt How to pronounce alert (audio) \

Definition of alert

 (Entry 1 of 3)

1a : watchful and prompt to meet danger or emergency an alert guard trying to stay alert to possible problems
b : quick to perceive and act mentally alert
2 : active, brisk elicited an alert response



Definition of alert (Entry 2 of 3)

1 : a state of careful watching and readiness especially for danger or opportunity on 24-hour alert
2a : an alarm or other signal of danger traffic alerts They sounded the alert.
b : an urgent notice … an alert to parents … about new immunization requirements.— Ann Schrader
3 : the period during which an alert is in effect
on the alert
: looking for or expecting something (such as danger or an opportunity) Drivers need to be on the alert for icy condition. always on the alert for a good bargain


alerted; alerting; alerts

Definition of alert (Entry 3 of 3)

transitive verb

1 : to call (someone) to a state of readiness : warn alerted the school board of a possible teachers' strike alert the authorities
2 : to make (someone) aware of something alerted the public to the dangers of pesticides

Other Words from alert


alertly adverb
alertness noun

Synonyms & Antonyms for alert

Synonyms: Adjective

Synonyms: Noun

Synonyms: Verb

Antonyms: Adjective

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Choose the Right Synonym for alert


watchful, vigilant, wide-awake, alert mean being on the lookout especially for danger or opportunity. watchful is the least explicit term. the watchful eye of the department supervisor vigilant suggests intense, unremitting, wary watchfulness. eternally vigilant in the safeguarding of democracy wide-awake applies to watchfulness for opportunities and developments more often than dangers. wide-awake companies latched onto the new technology alert stresses readiness or promptness in meeting danger or in seizing opportunity. alert traders anticipated the stock market's slide

intelligent, clever, alert, quick-witted mean mentally keen or quick. intelligent stresses success in coping with new situations and solving problems. an intelligent person could assemble it fast clever implies native ability or aptness and sometimes suggests a lack of more substantial qualities. clever with words alert stresses quickness in perceiving and understanding. alert to new technology quick-witted implies promptness in finding answers in debate or in devising expedients in moments of danger or challenge. no match for his quick-witted opponent

Examples of alert in a Sentence

Adjective An alert guard stopped the robbers. He was tired and had trouble staying alert while he was driving. She wasn't mentally alert enough to answer the questions. An alert watchdog guarded the door. Noun They sounded an alert when enemy planes were approaching the city. Medical officials have put out an alert to hospitals to look out for the virus. The government has issued a terrorism alert. Verb Several neighbors alerted the authorities when they noticed strangers acting suspiciously. The governor alerted island residents that a hurricane was coming. The teacher alerted the students that tests would be given the next day. See More
Recent Examples on the Web: Adjective The Collier County Sheriff’s Office released a missing person alert for Cross, 49, on Wednesday. Elisha Fieldstadt, NBC News, 12 Aug. 2022 It was described as alert but not eating on Monday by rescuers. Scott Gleeson, USA TODAY, 11 Aug. 2022 Most businesses are incredibly alert to the advent of new technologies. Agur Jõgi, Forbes, 10 Aug. 2022 State authorities have issued a missing and endangered person alert for a 68-year-old man who disappeared last week in south Alabama. Howard Koplowitz |, al, 10 Aug. 2022 Taiwan has put its military on alert and staged civil defense drills, while the U.S. has deployed numerous naval assets in the area. Arkansas Online, 7 Aug. 2022 Chicago authorities issued an alert Saturday afternoon for a man caught inappropriately touching women on camera. Dia Gill, Chicago Tribune, 7 Aug. 2022 Taiwan has put its military on alert and staged civil defense drills, but the overall mood remained calm on Friday. Ellen Knickmeyer, Zeke Miller, David Rising, Anchorage Daily News, 6 Aug. 2022 Tesla already tells drivers to remain alert, with their hands on the wheel, while using its advanced driver-assistance features. Rebecca Elliott, WSJ, 5 Aug. 2022 Recent Examples on the Web: Noun But the run-up is a reminder of the extent to which outsize moves for single stocks have become the norm in the era of Reddit traders, putting the broader investor community on alert for sudden distortions. Julia Horowitz, CNN, 4 Aug. 2022 More than 82 million Americans from California to New Hampshire are on alert for extreme heat Friday as the nation's deadly, unwavering heat wave pushes on. Emily Shapiro, ABC News, 22 July 2022 For this reason, health officials have asked this group to be on particular alert for symptoms. Katherine Hignett, Forbes, 30 June 2022 The city of Centreville posted a notice on social media asking people to be on alert for the suspect but for residents to lock their doors and stay inside. CBS News, 29 June 2022 In a world notorious for fakes and fraud, people might be expected to be on high alert for deception—but NFT fans had the wool pulled over their eyes by a fake Snoop Dogg at a huge conference in New York City this week. Chloe Taylor, Fortune, 24 June 2022 Polio has been detected in London’s wastewater system, U.K. health authorities said, putting clinics on high alert for an infectious disease that hasn’t been recorded in Britain for nearly four decades. Denise Roland, WSJ, 22 June 2022 Parts of Europe also are facing extreme heat, with Spain being on alert for an outbreak of intense wildfires. Editors, USA TODAY, 21 June 2022 As the still-rare monkeypox crops up around the world, including a San Francisco case now among five in California, people on the alert for the symptoms may not always see the typical patterns and blisters. Kellie Hwang, San Francisco Chronicle, 5 June 2022 Recent Examples on the Web: Verb It can be used to record a traffic stop, alert emergency contacts of your location and silence your phone. Maria Aguilar, USA TODAY, 24 July 2022 Health insurers are betting big on artificial intelligence and data analytics that scan medical records and then alert members on how to improve their health. Isabelle Bousquette, WSJ, 5 July 2022 Silverstein, meanwhile, said he was incredibly dismayed by the Instagram post Daily Harvest used to alert customers of the recall. Catherine Thorbecke And Jennifer Korn, CNN, 27 June 2022 Evo is experimenting with a new SMS text message program to alert customers about events near them. Corey Buhay, Outside Online, 13 June 2022 Video technology provides a non-invasive way to proactively support citizens and quickly alert staff if residents fall. Thomas Jensen, Forbes, 21 Apr. 2022 The Independent Community Bankers of America began flagging the potential changes to its members, prompting many of them in turn to alert their customers., 12 Oct. 2021 The House passed a bipartisan bill Wednesday that would enable law enforcement to set a system to alert people, warning them in case of a nearby active shooter. Merdie Nzanga, USA TODAY, 14 July 2022 Thornton police Chief Glenn Beckman said such notification from the Postal Service might have enabled his department, early on, to alert people who had mailed checks using the collection boxes. Mike Nolan, Chicago Tribune, 13 July 2022 See More

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'alert.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

First Known Use of alert


1618, in the meaning defined at sense 1a


1801, in the meaning defined at sense 1


circa 1868, in the meaning defined at sense 1

History and Etymology for alert


borrowed from French alerte, going back to Middle French a l'herte "on guard, on the watch," borrowed from Italian all'erta, originally in the collocation stare all'erta "to be on the watch," literally, "to be on the height" (with erta "height, hill, steep ascent," noun derivative from feminine of erto, past participle of ergere "to raise, elevate," going back to Vulgar Latin *ērgere, by syncope from Latin ērigere) — more at erect entry 1

Note: The earliest citation for the word in the Oxford English Dictionary suggests direct borrowing from Italian, or at least recognition of an Italian source: "In this place the Prince [of Orange] finding his rutters [cavalry soldiers] alert, (as the Italians say) with aduise of his valiant brother, hee sent his Trumpets to D. d' Alua …." (Sir Roger Williams, The Actions of the Lowe Countries, London, 1618, p. 27).


noun derivative of alert entry 1 (or borrowed from French alerte, derivative of alerte, adjective)


verbal derivative of alert entry 1 or alert entry 2

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Last Updated

16 Aug 2022

Cite this Entry

“Alert.” Dictionary, Merriam-Webster, Accessed 18 Aug. 2022.

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More Definitions for alert


\ ə-ˈlərt How to pronounce alert (audio) \

Kids Definition of alert

 (Entry 1 of 3)

1 : watchful and ready especially to meet danger But he was alert at night, too, on the road, always listening intently …— Lois Lowry, The Giver
2 : quick to understand and act An alert reader noticed the error in grammar.

Other Words from alert

alertly adverb The prairie dog sat alertly beside the opening of its burrow.



Kids Definition of alert (Entry 2 of 3)

1 : an alarm or signal of danger The police issued an alert.
2 : the period during which an alert is in effect We stayed indoors during the alert.
on the alert
: watchful against danger … the remark had set us all on the alert, straining ears and eyes …— Robert Louis Stevenson, Treasure Island


alerted; alerting

Kids Definition of alert (Entry 3 of 3)

: to make aware of a need to get ready or take action : warn The siren alerted us that a tornado was approaching.

More from Merriam-Webster on alert

Nglish: Translation of alert for Spanish Speakers

Britannica English: Translation of alert for Arabic Speakers


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