The Collaborative International Dictionary of English v.0.48:

Impel \Im*pel"\, v. t. [imp. & p. p. Impelled; p. pr. & vb. n.
   Impelling.] [L. impellere; pref. im- in + pellere, pulsum,
   to drive. See Pulse a beat, and cf. Impulse.]
   To drive or urge forward or on; to press on; to incite to
   action or motion in any way.
   [1913 Webster]

         The surge impelled me on a craggy coast. --Pope.

   Syn: To instigate; incite; induce; influence; force; drive;
        urge; actuate; move.
        [1913 Webster]

WordNet (r) 3.0 (2006):

impel
    v 1: urge or force (a person) to an action; constrain or
         motivate [syn: impel, force]
    2: cause to move forward with force; "Steam propels this ship"
       [syn: propel, impel]