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im·pet·u·ous (ĭm-pĕch-əs)
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adj.
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·petu·ous·ly adv.
im·petu·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).

The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2017 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
 

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