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1. Vigilantly attentive; watchful: alert to danger; an alert bank guard. See Synonyms at careful.
2. Mentally responsive and perceptive; quick.
3. Brisk or lively in action: the bird's alert hopping from branch to branch.
1. A signal that warns of attack or danger: Sirens sounded the alert for an air raid.
2. A condition or period of heightened watchfulness or preparation for action: Nuclear-armed bombers were put on alert during the crisis.
tr.v. a·lert·ed, a·lert·ing, a·lerts
To notify of approaching danger or action; warn: a flashing red light that alerted motorists to trouble ahead.
on the alert
Watchful and prepared for danger, emergency, or opportunity: bird watchers on the alert for a rare species.

[French alerte, from Italian all' erta, on the lookout : alla, to the, on the (from Latin ad illam, to that : ad, to; see ad- + illam, feminine accusative sing. of ille, that, the; see al- in Indo-European roots) + erta, lookout (from past participle of ergere, to raise, from Latin ērigere; see erect).]

a·lert′ly adv.
a·lert′ness n.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


a cheerful readiness, promptitude, or willingness; briskness. — alacritous, adj.
any actions aimed at keeping people on their toes. (Coined by Nubar Gulbenkian, 1964.)
-Ologies & -Isms. Copyright 2008 The Gale Group, Inc. All rights reserved.




  1. Alert as a bird in the springtime —George Moore
  2. Alert as a bloodhound at dinnertime —T. Coraghessan Boyle
  3. Bright as a bee —Julia O’Faolain
  4. Bright as a cigar band —Rita Mae Brown
  5. Bright as a salesman in a car showroom —Donald Seaman
  6. Bright-eyed as hawks —Walt Whitman, on the pioneer cowboys of the West
  7. (It helps to have a friend at City Hall with) an ear like a redskin, always to the ground —Arthur A. Cohen
  8. Ears … as sensitive as two microphones —Robert Culff
  9. Ears quick as a cat’s —Frank Swinnerton
  10. His brain [when free of restraint] skips like a lambkin —Calder Willingham
  11. His mind … was crackling like a high-tension wire —Cornell Woolrich
  12. Keen as a hawk’s eye —Barbara Howes
  13. Keen as robins —Frank Swinnerton
  14. (His alertness is nearly palpable,) keenness trembling within him like his pilot light —Philip Roth about Primo Levi, New York Times Book Review, October 12, 1986
  15. On the watch [for recurring problem] like a captain at sea, riding the unknown forces which may produce the known disaster all over again —Paul Horgan
  16. Quest about like a gun-dog —Lawrence Durrell
  17. Saw like Indian scouts and heard like blind people … and smelt like retrievers —Wilfrid Sheed
  18. Sharp-eyed as a lynx —Sir Walter Scott
  19. Wait like a set trap for a mouse —Anon
  20. Wide awake as a lie detector —Wallace Stegner
  21. Wide awake, brain cells flashing like free-game in a pinball machine —T. Coraghessan Boyle
Similes Dictionary, 1st Edition. © 1988 The Gale Group, Inc. All rights reserved.



(See also SHREWDNESS.)

Argus-eyed Vigilant, watchful; keen-eyed, alert. Argus was a mythical 100-eyed giant set by Juno to keep watch over the heifer Io. Only two of his eyes slept at a time. Mercury, however, was able to charm him to sleep, and slew him, whereupon Juno set Argus’ many eyes upon the peacock’s tail. Language ignores his failure and preserves his vigilance with Argus-eyed.

beat to the punch See ADVANTAGE.

keep one’s ear to the ground To be alert to what’s going on, to be abreast of rumors and hearsay, to be aware of the prevailing trends of public opinion. The expression is said to derive from a practice of plainsmen in the Old West. They reputedly believed that a neckerchief on the ground would amplify otherwise inaudible sounds, such as the beating of horses’ hooves. Consequently, they would often put an ear to a neckerchief so placed in order to discern another’s approach. This expression and its variants hold or have one’s ear to the ground date from the early part of this century, and still enjoy widespread currency.

What’s the gossip of the market, Tom? You fellows certainly do keep your ears to the ground. (Graham Greene, The Quiet American, 1955)

keep one’s eyes peeled To be on the qui vive; to be alert and watchful; to keep a sharp lookout. Although this version of the expression is currently popular, it appears to be a variant of keep one’s eyes skinned, which appeared in print presumably for the first time in The Political Examiner in 1833. The eyelid is the “skin” which must be “peeled” to permit one to see.

I kept my eyes peeled, but I didn’t see her in the afternoon crowd. (Munsey’s Magazine XXIV, 1901)

keep one’s weather eye open To be vigilant, watchful, or alert; to observe closely. This expression’s nautical origin refers to the diligent attentiveness of a sailor assigned to weather observation duty. The expression still carries its implication of astute observation.

Job returned in a great state of nervousness, and keeping his weather eye fixed upon every woman who came near him. (Rider Haggard, She: A History of Adventure, 1887)

no flies on [someone] Said of a person who is alert, astute, shrewd, or active, one not likely to be caught napping. The apparent allusion is to cattle which constantly move their tails in an attempt to discourage flying pests from settling and inflicting painful bites. Thus, the presence of flies implies stagnation or inactivity, while their absence implies the opposite.

There are no flies on Benaud. … No one will have to draw his attention to it. (Observer, April 23, 1961)

The expression is also used in reference to a business, project, or other matter which is thriving, reputable, and above reproach.

on one’s toes Alert, on the ball, ready to take advantage of an opportunity. A runner who starts a race “on his toes” has a decided edge over one who starts from a flatfooted position. Thus the phrase’s figurative sense of preparedness and alertness. Webster’s Third cites W. L. Gresham’s use of the expression:

In working for real money you’ve got to be on your toes.

on the ball Alert, keen, quick, sharp; intelligent, bright, perspicacious. The now common truncated phrase and its earlier, longer antecedents derive from sport, though which sport it is difficult to determine. Keep your eye on the ball probably came from a game such as tennis or baseball, where timing and concentration on the rapidly moving object are crucial. Have something on the ball is still used literally of pitchers with extraordinary control over the ball’s speed and direction. Being “on the ball” thus results from “having something on the ball” or “keeping one’s eyes on the ball” and is equivalent to them. A person on the ball is on top of things, in control, ready for all emergencies and contingencies. The phrase connotes the coordinated, nearly simultaneous anticipation and action of the accomplished athlete.

on the qui vive On the lookout, on the alert; watchful, aware, awake. “Qui vive?” was the French equivalent to the English “Who goes there?” a sentinel’s challenge to passers-by to identify themselves as friend or foe. “Qui vive?” called for a response of allegiance such as “Vive le roi” ‘long live the king’ or “Vive la France” ‘long live France.’ Use of the expression on the qui vive dates from at least 1726.

“What now?” cried Burtis, all on the qui vive. (Edward P. Roe in Harper’s Magazine, December, 1883)

quick on the draw Alert; quick-thinking; vigilant. This expression originated in the Old West, where a gunfighter’s survival depended upon the celerity with which he handled his weapon. The phrase is commonly used today to describe a keen-witted, sharp-minded person.

rough-and-ready See VITALITY.

take the ball before the bound To anticipate an opportunity, to be one step ahead of the game; to be overhasty or impetuous. Figurative use of this expression derives from a game such as cricket, tennis, or football. Whether such a move is advantageous or foolish depends on the situation. In the following citation, taking the ball before the bound has negative connotations.

It concerns you not to be over-hasty herein, not to take the ball before the bound, (lames Howell, Epistolae Ho-Elianae, 1645)

up to snuff See COMPETENCE.

Picturesque Expressions: A Thematic Dictionary, 1st Edition. © 1980 The Gale Group, Inc. All rights reserved.
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.alertness - the process of paying close and continuous attentionalertness - the process of paying close and continuous attention; "wakefulness, watchfulness, and bellicosity make a good hunter"; "vigilance is especially susceptible to fatigue"
attention - the faculty or power of mental concentration; "keeping track of all the details requires your complete attention"
jealousy - zealous vigilance; "cherish their official political freedom with fierce jealousy"-Paul Blanshard
2.alertness - a state of readiness to respondalertness - a state of readiness to respond; "alerting was indicated by the desynchronization of the EEG"
arousal - a state of heightened physiological activity
3.alertness - lively attentivenessalertness - lively attentiveness      
attentiveness - the trait of being observant and paying attention
Based on WordNet 3.0, Farlex clipart collection. © 2003-2012 Princeton University, Farlex Inc.


Collins Thesaurus of the English Language – Complete and Unabridged 2nd Edition. 2002 © HarperCollins Publishers 1995, 2002


The condition of being alert:
The American Heritage® Roget's Thesaurus. Copyright © 2013, 2014 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
تَنَبُّه، حَذَر


[əˈlɜːtnɪs] N (= mental acuteness) → lo espabilado, lo despierto; (= vigilance) → vigilancia f
Collins Spanish Dictionary - Complete and Unabridged 8th Edition 2005 © William Collins Sons & Co. Ltd. 1971, 1988 © HarperCollins Publishers 1992, 1993, 1996, 1997, 2000, 2003, 2005


[əˈlɜːrtnɪs] n
(= liveliness of mind) → vivacité f
Collins English/French Electronic Resource. © HarperCollins Publishers 2005


nAufmerksamkeit f; (as character trait) → Aufgewecktheit f; (of mind)Schärfe f; (of dog)Wachsamkeit f
Collins German Dictionary – Complete and Unabridged 7th Edition 2005. © William Collins Sons & Co. Ltd. 1980 © HarperCollins Publishers 1991, 1997, 1999, 2004, 2005, 2007


[əˈlɜːtnɪs] nprontezza
Collins Italian Dictionary 1st Edition © HarperCollins Publishers 1995


(əˈləːt) adjective
1. quick-thinking. She's very old but still very alert.
2. (with to) watchful and aware. You must be alert to danger.
a signal to be ready for action.
to make (someone) alert; to warn. The sound of gunfire alerted us to our danger.
aˈlertly adverb
aˈlertness noun
on the alert
on the watch (for). We were on the alert for any sound that might tell us where he was.
Kernerman English Multilingual Dictionary © 2006-2013 K Dictionaries Ltd.


n. estado de alerta.
English-Spanish Medical Dictionary © Farlex 2012


n estado de alerta, vigilancia
English-Spanish/Spanish-English Medical Dictionary Copyright © 2006 by The McGraw-Hill Companies, Inc. All rights reserved.
References in classic literature ?
That feeling of alertness and of readiness for anything was still further strengthened in him by the high opinion his fellow prisoners formed of him soon after his arrival at the shed.
She showed that alertness, that swiftness of reflection comes out in men before a battle, in conflict, in the dangerous and decisive moments of life--those moments when a man shows once and for all his value, and that all his past has not been wasted but has been a preparation for these moments.
With that alertness of the senses which is at once the marvel and despair of civilised peoples, they knew that the pirates were on the island from the moment one of them trod on a dry stick; and in an incredibly short space of time the coyote cries began.
She took my advice and was turning to put it into execution, when her eyes lighted on Oofty-Oofty, immediately before her, his body instinct with alertness and grace as he held the turn of the rope.
It was not so much that he had grown older; for though the traces of advancing life were visible he bore his age well, and seemed to retain a wiry vigour and alertness. But the former aspect of an intellectual and studious man, calm and quiet, which was what she best remembered in him, had altogether vanished, and been succeeded by a eager, searching, almost fierce, yet carefully guarded look.
Elton looked all happiness at this proposition; and nothing could exceed his alertness and attention in conducting them into his house and endeavouring to make every thing appear to advantage.
Here sat Wamba, with a small table before him, his heels tucked up against the bar of the chair, his cheeks sucked up so as to make his jaws resemble a pair of nut-crackers, and his eyes half-shut, yet watching with alertness every opportunity to exercise his licensed foolery.
Just as I had finished rolling up the compositions, the four o'clock bell rang; with my accustomed alertness in obeying that signal, I grasped my hat and evacuated the premises.
The alertness and rapacity of the hordes which infest these rapids, were immediately apparent.
He had straightened himself wonderfully, and there was a new alertness in his manner.
A scurry of feet in the sand, and low sniffings, stiffened him to alertness. It was as he had hoped.
Yet for all his slow movements there was a new alertness in his eyes and bearing.