WordNet sense 1 (an instinctive motive):

urge

WordNet sense 2 (a sudden desire):

caprice, whim

WordNet sense 3 ((electronics) a sharp transient wave in the normal electrical state (or a series of such transients)):

pulsation, pulse, pulsing

WordNet sense 4 (the electrical discharge that travels along a nerve fiber):

nerve impulse

WordNet sense 5 (an impelling force or strength):

momentum

WordNet sense 6 (the act of applying force suddenly):

impetus, impulsion