n.1 the act or an instance of impelling; a push.
2 an impetus.
3 Physics a an indefinitely large force acting for a very short time but producing a finite change of momentum (e.g. the blow of a hammer). b the change of momentum produced by this or any force.
4 a wave of excitation in a nerve.
5 mental incitement.
6 a sudden desire or tendency to act without reflection (did it on impulse).
Phrases and idioms:
impulse buying the unpremeditated buying of goods as a result of a whim or impulse.
Etymology: L impulsus (as IMPEL)