The Collaborative International Dictionary of English v.0.48:

Propulsion \Pro*pul"sion\, n. [Cf. F. propulsion. See Propel.]
   1. The act driving forward or away; the act or process of
      propelling; as, steam propulsion.
      [1913 Webster]

   2. An impelling act or movement.
      [1913 Webster]

            God works in all things; all obey
            His first propulsion.                 --Whittier.
      [1913 Webster]

WordNet (r) 3.0 (2006):

propulsion
    n 1: a propelling force
    2: the act of propelling [syn: propulsion, actuation]

Moby Thesaurus II by Grady Ward, 1.0:

53 Moby Thesaurus words for "propulsion":
   action and reaction, aeromotor, atomic power, bunt, butt, clout,
   compulsion, drive, driving force, electric power, electropower,
   horsepower, hydraulic power, hydroelectric power, impellent,
   impelling force, impetus, impulse, impulsion, incentive,
   incitement, irresistible force, jet power, jet propulsion,
   manpower, moment, momentum, motive power, nuclear power,
   piston power, power, power plant, pressure, propelling, propelment,
   pulsion, push, pushing, ram-jet propulsion, reaction,
   reaction propulsion, resojet propulsion, rocket power,
   rocket propulsion, shove, shoving, shunt, solar power, steam power,
   thermonuclear power, thrust, turbojet propulsion, water power