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

Definition of uranium 

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

Examples of uranium in a Sentence

Recent Examples on the Web

North Korea reportedly sits on anywhere between $6–10 trillion worth of untapped mineral wealth, including but not limited to molybdenium, uranium, gold, and silver. Brian Finlay, Fortune, "Businesses Are Salivating Over an Open North Korea. Should They Be?," 20 June 2018 About 360,000 Californians are served by water systems that violate state standards for nitrates, arsenic, uranium and other pollutants, according to a recent McClatchy investigation. Dale Kasler And Adam Ashton, sacbee, "California drinking water tax dies in budget compromise," 8 June 2018 The landlocked country, which won its independence from France in 1960, is rich in diamonds, gold, oil and uranium, but among the world’s 10 poorest countries per capita. David Woods, Indianapolis Star, "Avon's Isaac Guerendo has chance to do something at state track meet that hasn't been done in 105 years," 31 May 2018 On Friday, Iran's foreign minister, Javad Zarif, doubled down on Iran's right to enrich uranium, even as the country seeks a path to maintain the nuclear deal with the other adoptees. Nicole Gaouette, CNN, "US policy shifts on Mideast increase tensions in a region on edge," 12 May 2018 Iran has limited its capacity to enrich uranium, and by going back on the U.S. part of the bargain, Trump may be risking that. Brian Bennett, Time, "How Talks with North Korea Convinced Trump to Scrap the Iran Deal," 8 May 2018 There are also traces of ordinary U-238 even in weapons-grade uranium, and some types of thermonuclear weapons will also produce energy from U-238 fission. Andrew Karam, Popular Mechanics, "Nuclear Forensics: How Scientists Can Tell Whether North Korea Is Lying About Its Bomb Test," 7 Jan. 2016 And for a very long time the No. 1 source in the world for enriching uranium for the commercial sector was the U.S. DOE. Adrian Cho, Science | AAAS, "Undersecretary Paul Dabbar paints broad vision for Department of Energy science," 13 June 2018 This mostly holds up until 2002, when the US discovers that North Korea has secretly been enriching uranium for nuclear weapons. Brian Barrett, WIRED, "All the Times North Korea Promised to Denuclearize," 12 June 2018

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.

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First Known Use of uranium

circa 1797, in the meaning defined above

History and Etymology for uranium

New Latin, from Uranus

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Statistics for uranium

Last Updated

3 Nov 2018

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Time Traveler for uranium

The first known use of uranium was circa 1797

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More Definitions for uranium



English Language Learners Definition of uranium

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


ura·​ni·​um | \yu̇-ˈrā-nē-əm \

Kids Definition of uranium

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


ura·​ni·​um | \yu̇-ˈrā-nē-əm \

Medical Definition of uranium 

: 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 Chemical Elements Table

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Comments on uranium

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to clear from alleged fault or guilt

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