precipitate, impetuous, impulsive, foolish, hotheaded, thoughtless, reckless, headstrong, bold, careless, determined, audacious, heedless, madcap, unthinking, headlong, incautious, wild, precipitant, hasty, overhasty, unwary, injudicious, venturous, foolhardy, imprudent, venturesome, adventurous, daring, daredevil, jumping to conclusions, insuppressible, breakneck, irrational, fiery, furious, frenzied, passionate, immature, hurried, aimless, excited, feverish, indomitable, tenacious, frantic, indiscreet, quixotic, uncalculating, ill-advised, inadvisable, unconsidered, without thinking, unadvised, irresponsible, brash, precipitous, premature, sudden, burning one's fingers, harebrained, hotblooded, harum-scarum, game to the last, devil-may-care, rushing in where angels fear to tread.
Antonyms calm*, cautious, level-headed.
