[uh-ten-yoo-ey-shuh n]
See more synonyms for attenuation on
  1. the act of attenuating or the state of being attenuated.
  2. the process by which a virus, bacterium, etc., changes under laboratory conditions to become harmless or less virulent.
  3. Physics. a decrease in a property, as energy, per unit area of a wave or a beam of particles, occurring as the distance from the source increases as a result of absorption, scattering, spreading in three dimensions, etc.

Origin of attenuation

1585–95; (< Middle French) < Latin attenuātiōn- (stem of attenuātiō). See attenuate, -ion
Related formssub·at·ten·u·a·tion, noun Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

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Historical Examples of attenuation

British Dictionary definitions for attenuation


  1. the act of attenuating or the state of being attenuated
  2. the loss of energy suffered by radiation as it passes through matter, esp as a result of absorption or scattering
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for attenuation

early 15c., of persons, "emaciation;" of diet, "reduction," from Latin attenuationem (nominative attenuatio) "a lessening," noun of action from past participle stem of attenuare (see attenuate).

Online Etymology Dictionary, © 2010 Douglas Harper

attenuation in Medicine


  1. A dilution, thinning, or weakening of a substance, especially a reduction in the virulence of a pathogen through repeated inoculation, growth in a different culture medium, or exposure to heat, light, air, or other weakening agents.
  2. The energy loss of an ultrasonic beam as it passes through a material.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.