| 释义 |
WordReference Random House Learner's Dictionary of American English © 2024ra•di•um /ˈreɪdiəm/USA pronunciation n. [uncountable]- Chemistrya highly radioactive metallic element that is produced by the decay of uranium and has been used in the treatment of cancer.
WordReference Random House Unabridged Dictionary of American English © 2024ra•di•um (rā′dē əm),USA pronunciation n. - Chemistrya highly radioactive metallic element whose decay yields radon gas and alpha rays. Symbol: Ra;
at. wt.: 226;
at. no.: 88. - a lustrous rayon or silk fabric constructed in plain weave and used in women's apparel, lining, and drapery.
- Neo-Latin, equivalent. to Latin rad(ius) ray (see radius) + -ium -ium
- 1895–1900
Collins Concise English Dictionary © HarperCollins Publishers:: radium /ˈreɪdɪəm/ n - a highly radioactive luminescent white element of the alkaline earth group of metals. It occurs in pitchblende, carnotite, and other uranium ores, and is used in radiotherapy and in luminous paints. Symbol: Ra; atomic no: 88; half-life of most stable isotope, 226Ra: 1620 years; valency: 2; relative density: 5; melting pt: 700°C; boiling pt: 1140°C
- (as modifier): radium needle
Etymology: 20th Century: from Latin radius ray |