impulsive

Adjective

• characterized by undue haste and lack of thought or deliberation; (`brainish' is archaic)
  • a hotheaded decision
    
  • liable to such impulsive acts as hugging strangers
    
  • an impetuous display of spending and gambling
    
  • madcap escapades
    

• 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
    

• having the power of driving or impelling
  • a driving personal ambition
    
  • the driving force was his innate enthusiasm
    
  • an impulsive force
    

• without forethought
  • letting him borrow her car was an impulsive act that she immediately regretted
    

• proceeding from natural feeling or impulse without external stimulus
  • an impulsive gesture of affection
    

Related words

• Synonyms: 
  hotheaded , impetuous , madcap , tearaway(a) , brainish , capricious , whimsical , driving , unprompted