<p><strong>Noun</strong></p><ul><li>the influence of a particular feeling, mental state, etc.: to act under a generous impulse; to strike out at someone from an angry impulse</li><li>sudden, involuntary inclination prompting to action: to be swayed by impulse</li><li>an instance of this</li><li>a psychic drive or instinctual urge</li><li>an impelling action or force, driving onward or inducing motion</li><li>the effect of an impelling force; motion induced; impetus given</li><li>a progressive wave of excitation over a nerve or muscle fiber, having either a stimulating or inhibitory effect (Physiology)</li><li>the product of the average force acting upon a body and the time during which it acts, equivalent to the change in the momentum of the body produced by such a force (Mechanics)</li><li>a single, usually sudden, flow of current in one direction (Electricity)</li></ul><p><strong>Adjective</strong></p><ul><li>marked by or acting on impulse: an impulse buyer</li><li>bought or acquired on impulse: To reduce expenses, shun impulse items when shopping</li></ul>