fluorinePronunciation: /ˈflʊəriːn, ˈflɔː-/Definition of fluorine noun [mass noun] the chemical element of atomic number 9, a poisonous pale yellow gas of the halogen series. It is the most reactive of all the elements, causing very severe burns on contact with skin. (Symbol: F)Origin: early 19th century: from fluor (see fluorspar) + -ine4fluorine in other Oxford dictionaries Definition of fluorine in the US English dictionary
