1. Characterized by sudden and forceful energy or emotion; impulsive and passionate.
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.]

SYNONYMS   impetuous, heedless, hasty, headlong, precipitate, sudden. These adjectives describe abruptness or lack of deliberation. Impetuous suggests forceful impulsiveness or impatience: "[a race driver who was] flamboyant, impetuous, disdainful of death" (Jim Murray). Heedless implies carelessness or lack of responsibility or proper regard for consequences: "Hobbling down stairs with heedless haste, I set my foot full in a pail of water" (Richard Steele). 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, struck his head against the door to the east veranda, and probably broken his neck" (Mary Roberts Rinehart). Precipitate suggests impulsiveness and lack of due reflection: a precipitate decision. Sudden applies to what becomes apparent abruptly or unexpectedly: is given to sudden paroxysms of anger.

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.