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Pronunciation: i-ra'de-a'shun


  1. The subjective enlargement of a bright object seen against a dark background.
  2. Exposure to the action of electromagnetic radiation (heat, light, x-rays).
  3. The spreading of nervous impulses from one area in the brain or cord, or from a tract, to another tract.

[L. ir-radio, (in-r), pp. -radi-atus, to beam forth]

See Also: radiation

Further information

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© Copyright 2018 Wolters Kluwer. All Rights Reserved. Review date: Sep 19, 2016.