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[ak-tuh-nahyd] /ˈæk təˌnaɪd/
noun, Chemistry.
any element of the actinide series.
Origin of actinide
1940-45; actin- + -ide, on the model of lanthanide Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2017.
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British Dictionary definitions for actinide


a member of the actinide series Also called actinon
Word Origin
C19: from actino- + -ide
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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actinide in Medicine

actinide ac·ti·nide (āk'tə-nī'd)
Any of a series of chemically similar radioactive elements with atomic numbers ranging from 89 (actinium) through 103 (lawrencium).

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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actinide in Science
Any of a series of chemically similar metallic elements with atomic numbers ranging from 89 (actinium) to 103 (lawrencium). All of these elements are radioactive, and two of the elements, uranium and plutonium, are used to generate nuclear energy. See Periodic Table.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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