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radioactivity

 - 5 dictionary results

ra⋅di⋅o⋅ac⋅tiv⋅i⋅ty

  [rey-dee-oh-ak-tiv-i-tee]
Use radioactivity in a Sentence
–noun Physics, Chemistry.
the phenomenon, exhibited by and being a property of certain elements, of spontaneously emitting radiation resulting from changes in the nuclei of atoms of the element.
Also called activity.

Origin:
1895–1900; radio- + activity
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2009.
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ra·di·o·ac·tiv·i·ty   (rā'dē-ō-āk-tĭv'ĭ-tē)   
n.  

  1. Spontaneous emission of radiation, either directly from unstable atomic nuclei or as a consequence of a nuclear reaction.

  2. The radiation, including alpha particles, nucleons, electrons, and gamma rays, emitted by a radioactive substance.

The American Heritage® Dictionary of the English Language, Fourth Edition
Copyright © 2009 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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Cultural Dictionary

radioactivity

The emission of elementary particles by some atoms when their unstable nuclei disintegrate (see half-life). Materials composed of such atoms are radioactive. (See alpha radiation, beta radiation, and gamma radiation.)

The American Heritage® New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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Medical Dictionary

Main Entry: ra·dio·ac·tiv·i·ty
Pronunciation: -ak-'tiv-&t-E
Function: noun
Inflected Form: plural -ties
: the property possessed by some elements (as uranium) or isotopes (as carbon 14) of spontaneously emitting energetic particles (as electrons or alpha particles) by the disintegration of theiratomic nuclei
Merriam-Webster's Medical Dictionary, © 2002 Merriam-Webster, Inc.
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Medical Dictionary

radioactivity ra·di·o·ac·tiv·i·ty (rā'dē-ō-āk-tĭv'ĭ-tē)
n.

  1. Spontaneous emission of radiation, either directly from unstable atomic nuclei or as a consequence of a nuclear reaction.

  2. The radiation, including alpha particles, nucleons, electrons, and gamma rays, emitted by a radioactive substance.

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