The Collaborative International Dictionary of English v.0.48:

Propel \Pro*pel"\, v. t. [imp. & p. p. Propelled; p. pr. & vb.
   n. Propelling.] [L. propellere, propulsum; pro forward +
   pellere to drive. See Pulse a beating.]
   To drive forward; to urge or press onward by force; to move,
   or cause to move; as, the wind or steam propels ships; balls
   are propelled by gunpowder.
   [1913 Webster]

WordNet (r) 3.0 (2006):

propel
    v 1: cause to move forward with force; "Steam propels this ship"
         [syn: propel, impel]
    2: give an incentive for action; "This moved me to sacrifice my
       career" [syn: motivate, actuate, propel, move,
       prompt, incite]

Moby Thesaurus II by Grady Ward, 1.0:

56 Moby Thesaurus words for "propel":
   actuate, advance, animate, bowl, bunt, butt, compel, drive,
   drive on, egg on, energize, exhort, force, forward, foster,
   galvanize, get moving, give an impetus, give momentum, goad, impel,
   incite, launch, mobilize, motivate, move, move to action, nudge,
   pedal, pole, power, prick, prod, promote, prompt, push,
   put in motion, roll, row, send, set agoing, set going,
   set in motion, shove, shunt, spark, spur, start, stimulate, sweep,
   sweep along, thrust, treadle, troll, trundle, whip on