the range of wavelengths at which the earth’s atmosphere is transparent to radio waves.
a gap in ionospheric reflection that allows radio waves, with frequencies in the range 10 000 to 40 000 megahertz, to pass from or into space
radisectomy ra·di·sec·to·my (rā’dĭ-sěk’tə-mē) n. Variant of radectomy.
[rad-ish] /ˈræd ɪʃ/ noun 1. the crisp, pungent, edible root of the plant, Raphanus sativus, of the mustard family, usually eaten raw. 2. the plant itself. /ˈrædɪʃ/ noun 1. any of various plants of the genus Raphanus, esp R. sativus of Europe and Asia, cultivated for its edible root: family Brassicaceae (crucifers) 2. the root […]
[ra-dee-sawn] /ræ diˈsɔ̃/ noun 1. Pierre Esprit [es-pree] /ɛs pri/ (Show IPA), 1636?–1710? French fur trader and explorer in Canada.
[rey-dee-uh m] /ˈreɪ di əm/ noun 1. Chemistry. a highly radioactive metallic element whose decay yields gas and alpha rays. Symbol: Ra; atomic weight: 226; atomic number: 88. 2. a lustrous rayon or silk fabric constructed in plain weave and used in women’s apparel, lining, and drapery. /ˈreɪdɪəm/ noun 1. n. radioactive metallic element, 1899, […]
noun, Chemistry. 1. a substance, formed by decay of radon, that gives rise to radium B.