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radioactive

[rey-dee-oh-ak-tiv]
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adjective Physics, Chemistry.
  1. of, pertaining to, exhibiting, or caused by radioactivity.

Origin of radioactive

First recorded in 1895–1900; radio- + active
Related formsra·di·o·ac·tive·ly, adverbnon·ra·di·o·ac·tive, adjectiveun·ra·di·o·ac·tive, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for radioactive

Contemporary Examples

Historical Examples

  • But in order for radioactive breakdown to occur, time must pass.

    Equation of Doom

    Gerald Vance

  • "Eighty-five isn't nearly as radioactive as the elements akin to it," he said.

  • You see, the radioactive planets your men reported, one of them was—home.

    Alien Offer

    Al Sevcik

  • The hull was probably too radioactive to approach from the outside.

    The Lani People

    J. F. Bone

  • They said she was radioactive, but most of 'em wouldn't believe it.


British Dictionary definitions for radioactive

radioactive

adjective
  1. exhibiting, using, or concerned with radioactivity
Derived Formsradioactively, adverb
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

Word Origin and History for radioactive

adj.

1898, from French radio-actif, coined by Pierre and Marie Curie from radio-, comb. form of Latin radius (see radiation) + actif "active" (see active).

Online Etymology Dictionary, © 2010 Douglas Harper

radioactive in Medicine

radioactive

(rā′dē-ō-ăktĭv)
adj.
  1. Of or exhibiting radioactivity.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

radioactive in Culture

radioactive

A descriptive term for a material made up of atoms in which radioactivity occurs.

The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.