impulsive

1 caused by or suggestive of an irresistible urge an impulsive purchase of a very expensive jacket Synonyms besetting, driven, compulsive, obsessional, obsessiveRelated Words irrepressible, uncontrollable; automatic, instinctive, involuntary, knee-jerk, reflex, spontaneous; conditioned, mechanical; unconscious, unthinking, unwitting; capricious, unpredictable, whimsicalNear Antonyms unforced, voluntary, willful (or wilful); controllable, manageable, resistible

2 prone to sudden illogical changes of mind, ideas, or actions an impulsive woman who never seems to have the same opinion about anything for longer than 10 minutes Synonyms capricious, freakish, whimsicalRelated Words impetuous, mercurial, moody, temperamental, volatile; crankish, eccentric, flaky, quirky; arbitrary, erratic, fickle, inconstant, irregular, shaky, willful (or wilful); impractical, quixotic, quixotical, romantic, unrealistic, utopian, visionaryNear Antonyms equable; down-to-earth, earthy, hard-boiled, hardheaded, levelheaded, matter-of-fact, practical, pragmatic (also pragmatical), reasonable, sensible, tough-minded; commonsensical, grounded, logical, no-nonsense, rational, sane, sober, sobersided, sound; fast, fixed, hard-and-fast, immutable, inflexible, invariable, unalterable, unbending, unchangeable uncompromising, unrelenting, unyielding; changeless, constant, established, set, settled, stable, steadfast, steady, unchanging, unvarying