Source : Webster's Revised Unabridged Dictionary (1913)

Impulse \Im"pulse\, n. [L. impulsus, fr. impellere. See
   {Impel}.]
   1. The act of impelling, or driving onward with sudden force;
      impulsion; especially, force so communicated as to
      produced motion suddenly, or immediately.

            All spontaneous animal motion is performed by
            mechanical impulse.                   --S. Clarke.

   2. The effect of an impelling force; motion produced by a
      sudden or momentary force.

   3. (Mech.) The action of a force during a very small interval
      of time; the effect of such action; as, the impulse of a
      sudden blow upon a hard elastic body.

   4. A mental force which simply and directly urges to action;
      hasty inclination; sudden motive; momentary or transient
      influence of appetite or passion; propension; incitement;
      as, a man of good impulses; passion often gives a violent
      impulse to the will.

            These were my natural impulses for the undertaking.
                                                  --Dryden.

   Syn: Force; incentive; influence; motive; feeling;
        incitement; instigation.

Impulse \Im*pulse"\, v. t. [See {Impel}.]
   To impel; to incite. [Obs.] --Pope.

Source : WordNet®

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}]