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radon

[rey-don] /ˈreɪ dɒn/
noun, Chemistry
1.
a chemically inert, radioactive gaseous element produced by the decay of radium: emissions produced by outgassing of rock, brick, etc. are a health hazard. Symbol: Rn; atomic number: 86; atomic weight: 222.
Origin
1915-1920
1915-20; rad(ium) + -on2
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
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Examples from the web for radon
  • Exposure to radon is the second leading cause of lung cancer after smoking.
  • Prolonged exposure to elevated levels of radon can be harmful when found in homes.
  • radon gas is a naturally occurring radioactive gas that is invisible and odorless.
  • radon is a radioactive gas that comes from the natural decay of uranium that is found in nearly all soils.
  • By kicking radon out of homes every family can have safer, healthier air to breathe.
  • radon is a radioactive gas that cannot be seen, smelled or tasted.
  • radon is a naturally-occurring radioactive gas that may cause cancer, and may be found in drinking water and indoor air.
British Dictionary definitions for radon

radon

/ˈreɪdɒn/
noun
1.
a colourless radioactive element of the rare gas group, the most stable isotope of which, radon-222, is a decay product of radium. It is used as an alpha particle source in radiotherapy. Symbol: Rn; atomic no: 86; half-life of 222Rn: 3.82 days; valency: 0; density: 9.73 kg/m³; melting pt: –71°C; boiling pt: –61.7°C
Word Origin
C20: from radium + -on
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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Contemporary definitions for radon
noun

See radon gas

Dictionary.com's 21st Century Lexicon
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Word Origin and History for radon
n.

heaviest gaseous element, 1918, from German Radon, from radium (q.v.) + -on suffix of inert gases. The element was identified in radioactive decay of radium. Alternative name niton (from Latin nitens "shining") gained currency in France and Germany.

Online Etymology Dictionary, © 2010 Douglas Harper
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radon in Medicine

radon ra·don (rā'dŏn)
n.
Symbol Rn
A radioactive, largely inert gaseous element formed by the radioactive decay of radium and used as a radiation source in radiotherapy and research; its most stable isotope is Rn 222 with a half-life of 3.82 days. Atomic number 86; melting point -71°C; boiling point -61.7°C; specific gravity (solid) 4.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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radon in Science
radon
  (rā'dŏn)   
Symbol Rn
A colorless, odorless, radioactive element in the noble gas group. It is produced by the radioactive decay of radium and occurs in minute amounts in soil, rocks, and the air near the ground. Radon is used as a source of radiation for the treatment of cancer and other diseases. Its most stable isotope is Rn 222 with a half-life of 3.82 days. Atomic number 86; melting point -71°C; boiling point -61.8°C; specific gravity (solid) 4. See Periodic Table.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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radon in Culture
radon [(ray-don)]

A colorless, odorless, radioactive gas that is produced by the decay of radium in the soil.

Note: Radon seeping through the ground and into buildings is a major source of indoor air pollution and may represent a significant risk for lung cancer.
The American Heritage® New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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