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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.


a cheerful readiness, promptitude, or willingness; briskness. — alacritous, adj.
any actions aimed at keeping people on their toes. (Coined by Nubar Gulbenkian, 1964.)




  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



(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.

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



The condition of being alert:
تَنَبُّه، حَذَر


[əˈlɜːtnɪs] N (= mental acuteness) → lo espabilado, lo despierto; (= vigilance) → vigilancia f


[əˈlɜːrtnɪs] n
(= liveliness of mind) → vivacité f


nAufmerksamkeit f; (as character trait) → Aufgewecktheit f; (of mind)Schärfe f; (of dog)Wachsamkeit f


[əˈlɜːtnɪs] nprontezza


(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.


n. estado de alerta.


n estado de alerta, vigilancia
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