impulse

noun

1. an instinctive motive"profound religious impulses"
2. a sudden desire"he bought it on an impulse"
3. the electrical discharge that travels along a nerve fiber"they demonstrated the transmission of impulses from the cortex to the hypothalamus"
4. (electronics) a sharp transient wave in the normal electrical state (or a series of such transients)"the pulsations seemed to be coming from a star"
5. the act of applying force suddenly"the impulse knocked him over"
6. an impelling force or strength"the car's momentum carried it off the road"