impulse

(noun) an instinctive motive. Synonyms: urge. Example: "Profound religious impulses."

(noun) a sudden desire. Synonyms: caprice, whim. Example: "He bought it on an impulse."

(noun) the electrical discharge that travels along a nerve fiber. Synonyms: nerve impulse, nervous impulse, neural impulse. Example: "They demonstrated the transmission of impulses from the cortex to the hypothalamus."

(noun) (electronics) a sharp transient wave in the normal electrical state (or a series of such transients). Synonyms: pulsation, pulsing, pulse. Example: "The pulsations seemed to be coming from a star."

(noun) the act of applying force suddenly. Synonyms: impulsion, impetus. Example: "The impulse knocked him over."

(noun) an impelling force or strength. Synonyms: momentum. Example: "The car's momentum carried it off the road."