the influence of a particular feeling, mental state, etc.

to act under a generous impulse; to strike out at someone from an angry impulse.

sudden, involuntary inclination prompting to action

to be swayed by impulse.

an instance of this.

a psychic drive or instinctual urge.

an impelling action or force, driving onward or inducing motion.

the effect of an impelling force; motion induced; impetus given.

Physiology . a progressive wave of excitation over a nerve or muscle fiber, having either a stimulating or inhibitory effect.

Mechanics . 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.

Electricity . a single, usually sudden, flow of current in one direction.

marked by or acting on impulse

an impulse buyer.

bought or acquired on impulse

To reduce expenses, shun impulse items when shopping.

noun

actuation , appeal , bent , caprice , catalyst , desire , disposition , excitant , extemporization , fancy , feeling , flash * , goad , hunch , impellent , impulsion , incitation , incitement , inclination , influence , inspiration , instinct , itch * , lash , lust , mind , motivation , motive , notion , passion , spontaneity , spur , thought , urge , vagary , whim , whimsy , wish , yen , augmentation , beat , bump , drive , force , impetus , momentum , movement , pressure , propulsion , pulsation , pulse , push , rush , shock , shove , stroke , surge , thrust , vibration , encouragement , fillip , incentive , inducement , prod , stimulant , stimulation , stimulator , bee , boutade , conceit , freak , humor , megrim , impetuosity , impulsiveness , impulsivity , instigation , motion , nisus , resolve , stimulus , tendency , throb