IMPULSIVE

Definition

1. adjective proceeding from natural feeling or impulse without external stimulus. — synonyms: unprompted
2. adjective without forethought.
3. adjective having the power of driving or impelling. — synonyms: driving
4. adjective determined by chance or impulse or whim rather than by necessity or reason. — synonyms: capricious, whimsical
5. adjective characterized by undue haste and lack of thought or deliberation. — synonyms: hotheaded, impetuous, madcap, tearaway(a), brainish