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.]
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 ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.