radioactivity

radioactivity definition - medical

ra·di·o·ac·tiv·i·ty (rāˌdē-ō-ăk-tĭvˈĭ-tē)

noun
  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® Medical Dictionary Copyright © 2009 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

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