9 letters · 13 points in Scrabble
adjective characterized by undue haste and lack of thought or deliberation; ; ; ; ; (`brainish' is archaic)
adjective marked by violent force
originFrom Middle English impetuous, from Old French impetueux, from Late Latin impetuōsus (“violent”), from Latin impetus (“attack, violence”).
Etymology from Wiktionary, CC BY-SA 3.0