noun, often attributive
ra·​di·​um | \ ˈrā-dē-əm \

Definition of radium

: an intensely radioactive brilliant white metallic element that resembles barium chemically, occurs in combination in minute quantities in minerals (such as pitchblende or carnotite), emits alpha particles and gamma rays to form radon, and is used chiefly in luminous materials and in the treatment of cancer — see Chemical Elements Table

Examples of radium in a Sentence

Recent Examples on the Web

Of course, tobacco eventually joined the list of treacherous substances once thought to be healthy and subsequently discovered to be harmful, keeping excellent company alongside radium and mercury. Cathleen O'grady, Ars Technica, "What do we actually know about the risks of screen time and digital media?," 17 Oct. 2018 Those areas have struggled with radium and shrinking groundwater supplies. Fox News, "Book: Wisconsin quietly OK'd Lake Michigan water diversion," 18 Sep. 2018 In a journalism career that spanned 60 years, Gellhorn’s particular brand of nerve was rare as radium. Paula Mclain, Town & Country, "The Extraordinary Life of Martha Gellhorn, the Woman Ernest Hemingway Tried to Erase," 12 July 2018 Ash storage sites at the plant are leaking into surface water and groundwater upstream of drinking water intakes for more than 1 million people in the Charlotte region, the report says, calling the thallium and radium results alarming. Deon Roberts, charlotteobserver, "Groundwater at Duke Energy coal ash sites faulted for high radioactivity levels | Charlotte Observer," 20 Mar. 2018 In addition to beryllium, the soil contains lead and radioactive elements of thorium, radium and uranium. Keith Matheny, Detroit Free Press, "Radioactive soil from Ohio heads to Wayne County landfill next week," 22 June 2018 Back in Brandon, the city decisions on treating that radium are likely to take a year or more. CBS News, "Treating contaminated household water costly for cities – and consumers," 26 Jan. 2018 Treating Lacks’s cancer with crude radium implants—standard operating procedure in 1951—doctors were unable to save her life. Ryan P. Smith, Smithsonian, "Famed for “Immortal” Cells, Henrietta Lacks is Immortalized in Portraiture," 15 May 2018 Other tribes are also affected by the annual disposal of 100 million tons of coal ash, which is contaminated with arsenic, mercury, lead and radium. Evan Halper, latimes.com, "The Trump agenda has Native American tribes feeling under siege," 15 May 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'radium.' 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 radium

1899, in the meaning defined above

History and Etymology for radium

New Latin, from Latin radius ray

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Time Traveler for radium

The first known use of radium was in 1899

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More Definitions for radium



English Language Learners Definition of radium

: a radioactive element that is used medically in cancer treatments


ra·​di·​um | \ ˈrā-dē-əm \

Kids Definition of radium

: a strongly radioactive element found in very small quantities in various minerals (as pitchblende) and used in the treatment of cancer


noun, often attributive
ra·​di·​um | \ ˈrād-ē-əm \

Medical Definition of radium

: an intensely radioactive shining white metallic element that resembles barium chemically, that occurs in combination in minute quantities in minerals (as pitchblende or carnotite) principally as the isotope of mass number 226 formed from uranium 238, having a half-life of 1620 years, and emitting alpha particles and gamma rays to form radon, and that is used chiefly in luminous materials and in the treatment of cancer symbol Ra — see Chemical Elements Table

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More from Merriam-Webster on radium

Rhyming Dictionary: Words that rhyme with radium

Spanish Central: Translation of radium

Nglish: Translation of radium for Spanish Speakers

Britannica.com: Encyclopedia article about radium

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