uranium

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noun, often attributive ura·ni·um \yu̇-ˈrā-nē-əm\

Definition of uranium

  1. :  a silvery heavy radioactive polyvalent metallic element that is found especially in uraninite and exists naturally as a mixture of mostly nonfissionable isotopes — see element table

Recent Examples of uranium from the Web

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'uranium'. Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Origin and Etymology of uranium

New Latin, from Uranus


First Known Use: circa 1797


URANIUM Defined for English Language Learners

uranium

play
noun

Definition of uranium for English Language Learners

  • : a radioactive element that is used to make nuclear energy and nuclear weapons


URANIUM Defined for Kids

uranium

play
noun ura·ni·um \yu̇-ˈrā-nē-əm\

Definition of uranium for Students

  1. :  a radioactive metallic chemical element used as a source of atomic energy


Medical Dictionary

uranium

play
noun ura·ni·um \yu̇-ˈrā-nē-əm\

Medical Definition of uranium

  1. :  a silvery heavy radioactive polyvalent metallic element that is found especially in pitchblende and uraninite and exists naturally as a mixture of three isotopes of mass number 234, 235, and 238 in the proportions of 0.006 percent, 0.71 percent, and 99.28 percent respectively—symbol U; see element table



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