A Propellant

anything that propels:

1. fuel, oxidizer, reaction mass or mixture for one or more engines (especially internal combustion engines or jet engines) that is carried within a vehicle prior to use
2. the compressed gas in a pressurised container (especially an aerosol can) that is used to expel its content
3. the explosive (cordite, gunpowder, etc) found in ammunition cartridges

(fuel, oxidizer): prop (abbreviation)