From Longman Dictionary of Contemporary Englishradonra‧don /ˈreɪdɒn $ -dɑːn/ noun [uncountable] HCEa radioactive gas that is used in the treatment of diseases such as cancer. It is a chemical element: symbol Rn
Examples from the Corpus
radon• They are the noble gases: neon, argon, krypton, xenon, and radon.• If the soil is permeable enough radon can diffuse out before it decays.• As for radon, Rudy said looking for radon in drinking water would be extremely expensive and might not help public health.• But who do we blame for radon?• Environmentalists keep quiet because concern over radon in houses would divert attention from the campaign against nuclear power.• This is the so-called Action Level beyond which the occupier is advised to reduce the radon level.• The applicability of such data derived from uranium miners to the general population is central to the radon issue.Origin radon (1900-2000) radium 