impulse
     n 1: an instinctive motive; "profound religious impulses" [syn: {urge}]
     2: a sudden desire; "he bought it on an impulse" [syn: {caprice},
         {whim}]
     3: the electrical discharge that travels along a nerve fiber;
        "they demonstrated the transmission of impulses from the
        cortex to the hypothalamus" [syn: {nerve impulse}]
     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" [syn: {pulsation},
         {pulsing}, {pulse}]
     5: the act of applying force suddenly; "the impulse knocked him
        over" [syn: {impulsion}, {impetus}]
     6: an impelling force or strength; "the car's momentum carried
        it off the road" [syn: {momentum}]
Source: WordNet® 2.0