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[uh-ten-yoo-ey-shuh n] /əˌtɛn yuˈeɪ ʃən/
the act of attenuating or the state of being attenuated.
the process by which a virus, bacterium, etc., changes under laboratory conditions to become harmless or less virulent.
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 forms
subattenuation, noun Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2017.
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British Dictionary definitions for attenuation


the act of attenuating or the state of being attenuated
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
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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
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attenuation in Medicine

attenuation at·ten·u·a·tion (ə-těn'yōō-ā'shən)

  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.
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attenuation in Technology

The progressive reduction in amplitude of a signal as it travels farther from the point of origin.
For example, an electric signal's amplitude reduces with distance due to electrical impedance. Attenuation is usually measured in decibels [per metre?].
Attenuation does not imply appreciable modification of the shape of the waveform (distortion), though as the signal amplitude falls the signal-to-noise ratio will also fall unless the channel itself is noise free or the signal is amplified at some intermediate point(s) along the channel.
["Networking Essentials, second edition", Microsoft Corporation, pub. Microsoft Press 1997].

The Free On-line Dictionary of Computing, © Denis Howe 2010
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