impulsive

Adjective

• (adj.) impulsive, unprompted (proceeding from natural feeling or impulse without external stimulus) "an impulsive gesture of affection"
• (adj.) impulsive (without forethought) "letting him borrow her car was an impulsive act that she immediately regretted"
• (adj.) driving, impulsive (having the power of driving or impelling) "a driving personal ambition"; "the driving force was his innate enthusiasm"; "an impulsive force"
• (adj.) capricious, impulsive, whimsical (determined by chance or impulse or whim rather than by necessity or reason) "a capricious refusal"; "authoritarian rulers are frequently capricious"; "the victim of whimsical persecutions"
• (adj.) hotheaded, impulsive, impetuous, madcap, tearaway, brainish (characterized by undue haste and lack of thought or deliberation) "a hotheaded decision"; "liable to such impulsive acts as hugging strangers"; "an impetuous display of spending and gambling"; "madcap escapades"; (`brainish' is archaic)