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1. Acting or done quickly with little or inadequate thought.
2. Having or marked by violent force: impetuous, heaving waves.

[Middle English, violent, from Old French impetueux, from Late Latin impetuōsus, from Latin impetus, impetus; see impetus.]

im·pet′u·ous·ly adv.
im·pet′u·ous·ness n.
Synonyms: impetuous, hasty, headlong, precipitate
These adjectives describe abruptness or lack of deliberation. Impetuous suggests forceful impulsiveness or impatience: "[Martin Luther King] feared that an ill-prepared, impetuous demonstration would endanger ... the marchers" (Nick Kotz).
Hasty and headlong both stress hurried, often reckless action: "Hasty marriage seldom proveth well" (Shakespeare)."In his headlong flight down the circular staircase, ... [he] had pitched forward violently ... and probably broken his neck" (Mary Roberts Rinehart).
Precipitate suggests impulsiveness and lack of due reflection: "All my mistakes in life had flowed from that precipitate departure of mine" (Philip Roth).



early days Premature, overhasty; too early or soon; jumping the gun. In use since the 16th century, this British expression has a self-evident meaning but may sound awkward to American ears.

As regards the current year, it is early days to express any considered opinion, but trading conditions are bad. (Times, December 23, 1957)

from the hip Impulsively, impetuously, without preparation or thought; spontaneously, extempore. This expression is an abbreviated version of to shoot from the hip, literally to fire a handgun from the hip immediately upon drawing it from the holster and without taking formal aim.

… second thoughts about letting their man shoot from the hip quite so much as his nature prompted him to. (R. L. Maullin as quoted in Webster’s 6,000)

go off at half-cock To start prematurely; to leave unprepared; to act rashly, impetuously, or ill-advisedly; also, go off half-cocked. In this expression, half-cock refers to a position of a gun’s hammer which renders the weapon inoperable; thus, one is unprepared if the gun happens to go off at half-cock. Figuratively, the phrase implies acting on a whim with no preparatory measures.

Poor Doctor Jim! What disasters he brought down upon his country and his company by going off at half-cock. (Westminster Gazette, January, 1896)

Half-cocked is used adjectivally to mean ‘ill-prepared, ill-considered’ and by extension ‘foolish, silly, inane.’

head over heels See INTENSITY.

jump the gun To begin prematurely; to start early with the prospect of gaining an advantage. This expression’s origin lies in the false starts made by runners before the firing of the pistol that signals the race’s start. The phrase maintains common usage in the United States and Great Britain.

The Prime Minister has jumped the gun by announcing that it will take the form of government advances to building societies. (Economist, November, 1958)

on the spur of the moment See SPONTANEITY.

pell-mell In a recklessly hurried fashion; in a confused or disordered manner. This expression is derived from the medieval French sport pelle-melle, in which the object was to knock a ball through a hoop suspended at the end of an alley. Known as pall-mall in England, this sport involved much reckless, headlong rushing of the players into the alley, inspiring the coinage of the term pell-mell to describe this frenzied scurrying.

We were an absurd party of zealots, rushing pell-mell upon the floes with vastly more energy than discretion. (Elisha Kane, The U.S. Grinnell [First] Expedition in Search of Sir John Franklin, 1853)

take the ball before the bound See ALERTNESS.

trigger-happy Impetuous, reckless, rash, irresponsible; overanxious, over-eager; overly critical, quick to point out mistakes and faults in others. This term originally referred to an overeager gunman just itching to pull the trigger of his gun and cut somebody down. The term has since become generalized and is now applied to anyone inclined to hasty or ill-advised actions.

ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.impetuousness - rash impulsiveness
impulsiveness - the trait of acting suddenly on impulse without reflection
References in classic literature ?
I guess I'll be wanted," the pawnbroker observed, as he jerked open his shirt, tearing out the four buttons in his impetuousness and showing a Colt's .
On the instant he felt that marvelous return of the impetuousness, the intense excitement, the increasing expectancy of youth.
His "son and heir" Polemarchus has the frankness and impetuousness of youth; he is for detaining Socrates by force in the opening scene, and will not "let him off" on the subject of women and children.
They exhibit the impetuousness of a club that believe they are obliged to win.
He believes it was his initial naivety and impetuousness which served Lasan so well.
Experience has proved that at moments like this, we have to act responsibly and with a cool head and not with harsh words and impetuousness," he told ministers, who are fiercely divided over how to respond to mounting militant rocket fire on southern Israel.
that young people's immaturity and impetuousness make them less
The idea that education policy could be shaped at a legislature talking shop is indicative of the impetuousness that plagues public life.
At 21, Shelvey still retains a degree of impetuousness evident when he found himself in the middle of spot-kick controversy at Tottenham three weeks ago, but he has already played over 130 senior games since making his debut as a 16-year-old at Charlton and has great experience for someone of his tender years.
Well, Morsi's mistakes, his impetuousness and his uncompromising attitude concerning the amending of the constitution could be criticized, but how could they pit a democratically elected president and a coup general against each other?
As such, he's not within a stone of fellow seven-year-old Sprinter Sacre for the 2014 Champion Chase, but his continuing impetuousness surely rules out three miles for now.