countable/uncountable a sudden strong feeling that you must do somethingan impulse to do something: Jenny felt a sudden impulse to play some music.
control/resist an impulse: She struggled to resist the impulse to laugh.
on (an) impulse (=because you suddenly feel that you want to): He saw them get into the car and on an impulse he followed them.
act on impulse: Acting on impulse, he knocked on her door.