impetuous (adj) - given to impulsive or rash action; hasty or eager; having great impetus or violent force [im-pech-oo-uhs]
BREAKDOWN: IM- (in) + PET- (rush) + -OUS (full of)
impetus is a force that impels; an impulse or stimulus
“Under the magnetism of friendship the modest man becomes bold; the shy, confident; the lazy, active; and the impetuous, prudent and peaceful.” —William Makepeace Thackeray