any of a class of compounds produced by substituting fluorine for hydrogen in a hydrocarbon, and characterized by great chemical stability: used chiefly as a lubricant, refrigerant, fire extinguishing agent, and in industrial and other applications in which chemical, electrical, flame, and heat resistance is essential; banned as an aerosol propellant in the U.S. because of concern about ozone layer depletion. Cf. chlorofluorocarbon, chlorofluoromethane.