a substance that propels something, in particular:
an inert fluid, liquefied under pressure, in which the active contents of an aerosol are dispersed:the main uses of CFCs are in aerosols as propellants [mass noun]:aerosols are wastefully packaged, because they contain a lot of propellant as well as the product
an explosive that fires bullets from a firearm:the common gun propellants are either nitrocellulose or a mixture of nitrocellulose and nitroglycerine [mass noun]:the company produced all sizes of propellant for weapons
a substance used as a reagent in a rocket engine to provide thrust:rocket propellants
