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[floo r-een, -in, flawr-, flohr-] /ˈflʊər in, -ɪn, ˈflɔr-, ˈfloʊr-/
noun, Chemistry
the most reactive nonmetallic element, a pale-yellow, corrosive, toxic gas that occurs combined, especially in fluorite, cryolite, phosphate rock, and other minerals. Symbol: F; atomic weight: 18.9984; atomic number: 9.
Origin of fluorine
1805-15; fluor(ic) + -ine1 Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for fluorine
  • Other patches of stone have been bleached white by chlorine and fluorine gases pouring from the vent.
  • Because of their fluorine content, they're persistent.
  • At high pH, the fluorine groups become charged and protect the membrane from chlorine and clogging.
  • Fluorosis is more common than arsenic poisoning because high-fluorine coal is combined with high-fluorine clay to make briquettes.
  • Many easily available elements such as sodium and fluorine are dangerous if touched, inhaled or allowed to combine with others.
  • The membrane under development uses fluorine materials that respond to pH levels in the water.
  • Don't even get me started on fluorine and sodium or any of the proteins.
  • fluorine is a naturally-occurring, pale yellow-green gas with a sharp odor.
  • Uranium hexafluoride is a chemical compound consisting of one atom of uranium combined with six atoms of fluorine.
British Dictionary definitions for fluorine


a toxic pungent pale yellow gas of the halogen group that is the most electronegative and reactive of all the elements, occurring principally in fluorspar and cryolite: used in the production of uranium, fluorocarbons, and other chemicals. Symbol: F; atomic no: 9; atomic wt: 18.9984032; valency: 1; density: 1.696 kg/m³; relative density: 1.108; freezing pt: –219.62°C; boiling pt: –188.13°C
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for fluorine

non-metallic element, 1813, coined by English chemist Sir Humphry Davy (1778-1829) from fluorspar ("calcium fluoride," modern fluorite), the late 18c. name of the mineral where it was first found; see fluor + chemical suffix -ine (2). Not isolated until 1886.

Online Etymology Dictionary, © 2010 Douglas Harper
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fluorine in Medicine

fluorine fluor·ine (flur'ēn', -ĭn, flôr'-)
Symbol F
A highly corrosive poisonous gaseous halogen element, the most reactive of all the elements. Atomic number 9; atomic weight 18.9984; melting point -219.62°C; boiling point -188.14°C (at 1 atmosphere); specific gravity of liquid 1.108 (at boiling point); valence 1.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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fluorine in Science
Symbol F
A pale-yellow, poisonous, gaseous element of the halogen group. It is highly corrosive and is used to separate certain isotopes of uranium and to make refrigerants and high-temperature plastics. It is also added in fluoride form to the water supply to prevent tooth decay. Atomic number 9; atomic weight 18.9984; melting point -223°C; boiling point -188.14°C; specific gravity of liquid 1.108 (at boiling point); valence 1. See Periodic Table.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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