Definitions for radonˈreɪ dɒn
Random House Webster's College Dictionary
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; at. no.: 86; at. wt.: 222.
Origin of radon:
< G Radon (1918); see radium , -on2
radon, Rn, atomic number 86(noun)
a radioactive gaseous element formed by the disintegration of radium; the heaviest of the inert gasses; occurs naturally (especially in areas over granite) and is considered a hazard to health
A radioactive chemical element (symbol Rn, formerly Ro) with atomic number 86, one of the noble gases.
Origin: Contraction of radium emanation, since the element appears in the radioactive decay of radium.
U.S. National Library of Medicine
Radon. A naturally radioactive element with atomic symbol Rn, atomic number 86, and atomic weight 222. It is a member of the noble gas family and released during the decay of radium and found in soil. There is a link between exposure to radon and lung cancer.