Pronunciation: (rā'dē-um), [key]
1. Chem.a highly radioactive metallic element whose decay yields radon gas and alpha rays. Symbol: Ra; at. wt.: 226; at. no.: 88.
2. a lustrous rayon or silk fabric constructed in plain weave and used in women's apparel, lining, and drapery.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.