impulsive (
http://definr.com/impulsive)
adj 1: proceeding from natural feeling or impulse without external
stimulus; "an impulsive gesture of affection" [syn:
unprompted]
2: without forethought; "letting him borrow her car was an
impulsive act that she immediately regretted"
3: having the power of driving or impelling; "a driving
personal ambition"; "the driving force was his innate
enthusiasm"; "an impulsive force" [syn:
driving]
4: 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" [syn:
capricious,
whimsical]
5: 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) [syn:
hotheaded,
impetuous,
madcap,
tearaway(a),
brainish]