A soft, silver-white, ductile, metallic chemical element, one of the alkali metals and the most electropositive of all the elements: it ignites in air, reacts vigorously with water, and is used in photoelectric cells: symbol, Cs; at. no. 55: a radioactive isotope (cesium-137) with a half-life of 30.17 years is produced by fission and is used in cancer research, radiation therapy, etc.
Webster's New World
(US) Alternative spelling of caesium.
Origin of Cesium
From Latin caesius bluish gray (from its blue spectral lines)
From American Heritage Dictionary of the English Language, 5th Edition
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Words Starting With C and Ending With M