A gaseous chemical element, atomic no. 9, atomic wt. 18.9984032; 18F (half-life of 1.83 h) is used as a diagnostic aid in various tissue scans. [L. fluere, flow]
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fluo·rine 'flu̇(-ə)r-.ēn, -ən n a nonmetallic monovalent halogen element that is normally a pale yellowish flammable irritating toxic gas symbol F see ELEMENT (table)
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flu·o·rine (F) (floorґēn) [L. fluor any of a group of minerals, including fluorite (calcium fluoride), used as metallurgical fluxes, from fluere to flow] a nonmetallic, gaseous element, belonging to the halogen group; atomic number 9, atomic weight 18.998. Fluorine, in the form of fluoride, is incorporated into the structure of bone and teeth and provides protection against dental caries; an excess of fluorine may result in fluorosis.Medical dictionary. 2011.