ac·​ti·​nide | \ ˈak-tə-ˌnīd How to pronounce actinide (audio) \

Definition of actinide

: any of the series of elements with increasing atomic numbers that begins with actinium or thorium and ends with lawrencium — see Periodic Table

Examples of actinide in a Sentence

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Uranium is currently the actinide of choice for the industry, used (sometimes with a little plutonium) in 100 percent of the world’s commercial reactors. Richard Martin, WIRED, "Uranium Is So Last Century — Enter Thorium, the New Green Nuke," 21 Dec. 2009

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

First Known Use of actinide

1945, in the meaning defined above

History and Etymology for actinide

acti(nium) + (lantha)nide

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Time Traveler for actinide

The first known use of actinide was in 1945

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to mark by some ceremony or observation

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