radon
1. [ noun ] (chemistry) 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
Synonyms: atomic_number_86 Rn
Related terms: chemical_element noble_gas
Similar spelling:   ration
  ratan
  Radin
  radome
  Radney
  rattan
  radian