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From The Collaborative International Dictionary of English v.0.48:
Uranium \U*ra"ni*um\, n. [NL., from Uranus the planet. See Uranus.] (Chem.) An element of the chromium group, found in certain rare minerals, as pitchblende, uranite, etc., and reduced as a heavy, hard, nickel-white metal which is quite permanent. Its yellow oxide is used to impart to glass a delicate greenish-yellow tint which is accompanied by a strong fluorescence, and its black oxide is used as a pigment in porcelain painting. Symbol U. Atomic weight 239. [1913 Webster] Note: Uranium was discovered in the state of an oxide by Klaproth in 1789, and so named in honor of Herschel's discovery of the planet Uranus in 1781. [1913 Webster] Uran-ocher