1. radon, Rn, atomic number 86, chemical element, element, noble gas, inert gas, argonon

usage: 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

2. registered nurse, RN, nurse

usage: a graduate nurse who has passed examinations for registration

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See also: rn (Dictionary)