- fluorine, F, atomic number 9 - a nonmetallic univalent element belonging to the halogens; usually a yellow irritating toxic flammable gas; a powerful oxidizing agent; recovered from fluorite or cryolite or fluorapatite
--1 is a kind of chemical element, element; gas; halogen
--1 is a substance offluorite, fluorspar, fluor; fluorapatite; cryolite, Greenland spar