A lot vs. Alot: 9 Grammatical Pitfalls
early 15c., originally in reference to medicine that reduces swelling or humors, from Middle French impulsif or directly from Medieval Latin impulsivus, from Latin impuls-, past participle stem of impellere (see impel). Of persons, "rash, characterized by impulses," from 1847.
impulsive im·pul·sive (ĭm-pŭl'sĭv)
Inclined or tending to act on impulse rather than thought.
Motivated by or resulting from impulse.