background radiation Hear it!

background radiation definition

background radiation

  1. Astron. low-intensity, multidimensional microwave radiation present in space: its existence is used to support the validity of the big-bang theory since it is thought to be a remnant of the original explosion
  2. Physics low levels of natural radiation existing on earth as a result of high-energy cosmic rays, the radioactive decay of rock, etc.

Webster's New World College Dictionary Copyright © 2009 by Wiley Publishing, Inc., Cleveland, Ohio.
Used by arrangement with John Wiley & Sons, Inc.

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