\ 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 Daemon gave her and her eyes trying to stay alert as someone drones on in the background. Omar L. Gallaga, Washington Post, 12 Sep. 2022 So stay alert and then ride a bucolic 15 more miles past farms and vineyards, a pioneer graveyard, many cows and some horses into Forest Grove. oregonlive, 12 Sep. 2022 The incident came as tensions were high at many federal facilities and the FBI was on alert following threats against the agency over its raid at former President Donald Trump's Florida home last week. Harold Maass, The Week, 15 Aug. 2022 These entrepreneurs must remain very alert and make brilliant and quick business decisions. Josh Wilson, Forbes, 16 June 2022 Tesla states that drivers using Autopilot must remain alert and be prepared to take full control of the vehicle at a moment’s notice. Matt Mcfarland, CNN, 15 June 2022 Kansas Governor Laura Kelly urged residents to remain alert as severe weather moved across the state Friday night. Dennis Romero, NBC News, 30 Apr. 2022 But despite the good news, experts are pleading with Americans to remain alert, as the highly infectious delta variant continues to circulate. Arielle Mitropoulos, ABC News, 22 Oct. 2021 Caring adults who stay alert to digital dilemmas, set useful boundaries, and offer empathy, connection, and validation. WIRED, 22 Aug. 2022 Recent Examples on the Web: Noun My head snapped up, every nerve ending suddenly on alert. Good Housekeeping, 16 Sep. 2022 The explosion put nearby Harvard University and the Massachusetts Institute of Technology on alert as investigators responded to another suspicious package located near a prominent art museum. Ashley R. Williams, USA TODAY, 14 Sep. 2022 Four schools were put on alert as the shooting unfolded early Friday, Adams said, and animal control was called to care for two cats and a dog found in the residence. Justin Wm. Moyer, Washington Post, 9 Sep. 2022 On Friday evening, residents of Oakridge, Westfir and the High Prairies area were evacuated and encouraged to head west after being on alert the past few days. oregonlive, 9 Sep. 2022 Castillo told the Union-Tribune that international borders and airports are on alert, but Francis might already be across the Rio Grande. María Luisa Paúl, Anchorage Daily News, 6 Sep. 2022 There’s been no indication that this outbreak has spread much further than the states of Kerala, Tamilnadu, and Odisha in India yet, although neighboring states have been on alert, according to the letter. Bruce Y. Lee, Forbes, 26 Aug. 2022 But there's a reason why a single case puts health officials on alert. Brenda Goodman, CNN, 23 Aug. 2022 The majority of Arizona and New Mexico are under flood watches through Saturday night, leaving more than 10 million Americans on alert. Kenton Gewecke, ABC News, 20 Aug. 2022 Recent Examples on the Web: Verb ToxMod can then alert a human moderator or, in some cases, automatically mute offending users. Rachel Metz, CNN, 5 May 2022 But a loss will alert Barstool to send you a free bet of equal value, up to $1,000. Xl Media, cleveland, 8 Sep. 2022 But after the victims wire that money, their banks alert them that the check from the scammers was bogus. Ron Hurtibise, Sun Sentinel, 8 Sep. 2022 This iPhone texting tip basically will alert you every time iOS attempts to autocorrect a word. Yoni Heisler, BGR, 6 Sep. 2022 Most connected charging stations can also alert EV charging smartphone apps if a station is available. Jordan Ramer, Forbes, 16 Aug. 2022 The funeral employee did not alert the family of Kyung Ja Kim until hours later, according to the suit. Michelle Watson, CNN, 27 July 2022 Those workers will alert police to threats, point people to homeless-service agencies and keep an eye on vulnerable people. Los Angeles Times, 5 July 2022 Any customer who feels worried or unsafe should absolutely alert the bartender and/or security staff. Amy Dickinson, oregonlive, 12 June 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

21 Sep 2022

Cite this Entry

“Alert.” Dictionary, Merriam-Webster, Accessed 1 Oct. 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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