WordNet (r) 3.0 (2006):

propellant
    adj 1: tending to or capable of propelling; "propellant fuel for
           submarines"; "the faster a jet plane goes the greater its
           propulsive efficiency"; "universities...the seats of
           propulsive thought" [syn: propellant, propellent,
           propelling, propulsive]
    n 1: any substance that propels [syn: propellant,
         propellent]

Moby Thesaurus II by Grady Ward, 1.0:

92 Moby Thesaurus words for "propellant":
   active, airscrew, alcohol, benzine, briquette, burnable, butane,
   carbon, catalyst, charcoal, charge, coal, coke, combustible, dope,
   driver, driving, ethane, ethanol, exhaust, fan, fireball, firing,
   flammable, flammable material, fuel, fuel additive, fuel dope, gas,
   gas carbon, gasoline, heptane, hexane, impeller, impelling,
   impetus, impulse, in motion, incentive, incitation, inflammable,
   inflammable material, isooctane, jet fuel, jet propulsion,
   kerosene, liquid oxygen, methane, methanol, mobile, motile,
   motivation, motivational, motive, motor, moving, natural gas,
   octane, oil, paddle wheel, paraffin, peat, pentane, piston, prop,
   propane, propeller, propelling, propulsion charge, propulsive,
   propulsor, propulsory, provocative, pulsive, pushing,
   reaction propulsion, rocket fuel, rocket propulsion, rotor, screw,
   screw propeller, shoving, spur, stimulant, stirring, thrust,
   transitional, traveling, turbine, turf, twin screws, wheel