- An odorless, colorless radioactive gas given off by some soils and rock with a short half-life (less than four days). If found in homes in sufficient concentrations, radon exposure can cause health problems.
- A colorless noble gas whose atomic number is 86. It is the densest known gas, and has over 30 known isotopes, all of which are unstable. It is used in the treatment of diseases, such as cancer, and as a neutron source. Its chemical symbol is Rn.
- chemical symbolRn
- noun a radioactive gas, formed from the radioactive decay of radium, and used in capsules called radon seeds to treat cancers inside the body