uranium Meaning, Definition & Usage

  1. noun a heavy toxic silvery-white radioactive metallic element; occurs in many isotopes; used for nuclear fuels and nuclear weapons
    U; atomic number 92.

WordNet

U*ra"ni*um noun
Etymology
NL., from Uranus the planet. See Uranus.
Definitions
  1. (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. <--radioactive, U-235 isotope is used in atomic fission, in bombs or power plants --> ✍ 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.

Webster 1913