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
例句
用作名词 (n.)
Radon is the daughter of radium. 氡是镭的子体。
Where does the indoor radon come from? 室内氡气是从哪里而来?