Source : Webster's Revised Unabridged Dictionary (1913)

Impulsion \Im*pul"sion\, n. [L. impulsio: cf. F. impulsion. See
   {Impel}.]
   1. The act of impelling or driving onward, or the state of
      being impelled; the sudden or momentary agency of a body
      in motion on another body; also, the impelling force, or
      impulse. ``The impulsion of the air.'' --Bacon.

   2. Influence acting unexpectedly or temporarily on the mind;
      sudden motive or influence; impulse. ``The impulsion of
      conscience.'' --Clarendon. ``Divine impulsion prompting.''
      --Milton.

Source : WordNet®

impulsion
     n 1: a force that moves something along [syn: {drift}, {impetus}]
     2: the act of applying force suddenly; "the impulse knocked him
        over" [syn: {impulse}, {impetus}]