radioactive

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

Origin:
1895–1900; radio- + active

radioactively, adverb
nonradioactive, adjective
unradioactive, adjective
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
Cite This Source Link To Radioactive
Collins
World English Dictionary
radioactive (ˌreɪdɪəʊˈæktɪv)
 
adj
exhibiting, using, or concerned with radioactivity
 
radio'actively
 
adv

Collins English Dictionary - Complete & Unabridged 10th Edition
2009 © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009
Cite This Source
Etymonline
Word Origin & History

radioactive
1898, from Fr. radio-actif, coined by Pierre and Marie Curie from radio-, comb. form of L. radius (see radiation) + actif (fem. active) "active."
Online Etymology Dictionary, © 2010 Douglas Harper
Cite This Source
American Heritage
Medical Dictionary

radioactive ra·di·o·ac·tive (rā'dē-ō-āk'tĭv)
adj.
Of or exhibiting radioactivity.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
Cite This Source
American Heritage
Cultural Dictionary

radioactive definition


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

The American Heritage® New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
Cite This Source
Example sentences
The raindrops that keep falling on our heads may not cause our hair to fall out
  but they are, nevertheless, radioactive.
It would also not itself become radioactive by absorbing neutrons.
Around the world radioactive nuclear reactors in derelict submarines dot the
  seafloor.
Radioactive sulphur signal adds to evidence of catastrophe.
Copyright © 2014 Dictionary.com, LLC. All rights reserved.
  • Please Login or Sign Up to use the Recent Searches feature