noun, often attributive
ra·​di·​um | \ ˈrā-dē-əm How to pronounce radium (audio) \

Definition of radium

: an intensely radioactive metallic chemical element that 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 the treatment of cancer and in radiographic devices — see Chemical Elements Table

Examples of radium in a Sentence

Recent Examples on the Web In 2019, the Lake County Public Works Department issued a letter to Lake Zurich asking the village to remove radium produced by its ion exchange process from the wastewater stream sent to Lake County, according to Village Manager Ray Keller. Elizabeth Owens-schiele, chicagotribune.com, 8 Mar. 2022 Why Marie: The first woman to win the Nobel Prize for Physics, Marie Curie is best known for her discovery of both polonium and radium, as well as fundamentally changing our understanding of radioactivity. Yola Robert, Forbes, 31 Jan. 2022 At present, the local system filters the radium and it’s safe to drink. Jesse Wright, chicagotribune.com, 2 Feb. 2022 This 14 by 14 inch, over-the-counter device takes minutes to set up and removes 83 contaminants, such as lead, chromium, copper, radium, chlorine, and more. Kayla Hui, Health.com, 6 Jan. 2022 Other notorious patent medicines common in this era include Radithor, a radioactive tonic made from dissolved radium. David Reamer, Anchorage Daily News, 21 Nov. 2021 Marie Curie was a Nobel-prize-winning French physicist who discovered polonium and radium — later leading to the development of X-rays and the establishment of radiation therapy for cancer. Joanna Dutra, Forbes, 26 Oct. 2021 Only five women are currently buried at the Pantheon including Nobel Prize physicist and chemist Marie Curie who discovered radium and polonium. Ibtissem Guenfoud, ABC News, 23 Aug. 2021 The Curies hadn’t isolated pure radium, only compounds containing it. Andrew Crumey, WSJ, 30 July 2021 See More

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.

First Known Use of radium

1899, in the meaning defined above

History and Etymology for radium

New Latin, from Latin radius ray

Learn More About radium

Dictionary Entries Near radium

radish tree


radium clock

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Statistics for radium

Last Updated

14 Apr 2022

Cite this Entry

“Radium.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/radium. Accessed 16 May. 2022.

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More Definitions for radium


ra·​di·​um | \ ˈrā-dē-əm How to pronounce radium (audio) \

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 How to pronounce radium (audio) \

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

More from Merriam-Webster on radium

Nglish: Translation of radium for Spanish Speakers

Britannica.com: Encyclopedia article about radium


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