fluorine

n. nonmetallic chemical element

Distinguished from fluorene and fluorone. Fluorine (IPA: , , meaning "to flow"), is the chemical element with the symbol F and atomic number 9. Atomic fluorine is univalent and is the most chemically reactive and electronegative of all the elements. In its elementally isolated (pure) form, fluorine is a poisonous, pale, yellowish brown gas, with chemical formula F2. Like other halogens, molecular fluorine is highly dangerous; it causes severe chemical burns on contact with skin.
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Fluorine /flu·o·rine/ a chemical element, at. no. 9. fluor·ine n. Symbol F A highly corrosive, toxic, gaseous halogen element. [more]Fluorine - Community and Resources

Noun
1. 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
(synonym) F, atomic number 9
(hypernym) chemical element, element
(substance-holonym) fluorite, fluorspar, fluor

n. fluorite, common mineral, fluorspar