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the act of or the state of being .
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.
Historical Examples

Moreover, the fiefs dependent on the Gascon duchy had fallen away with the attenuation of the duke’s domain.
The History of England T.F. Tout

The rapidity of the action diminished with the attenuation of the vapour.
Fragments of science, V. 1-2 John Tyndall

The occupant of the bed appears almost in a sitting position, propped up by pillows, marble pale, and thin to attenuation.
Floyd Grandon’s Honor Amanda Minnie Douglas

It is to be given at the first attenuation three times daily in half gr.
An Epitome of Homeopathic Healing Art B. L. Hill

The heat is at this time generally 75°, if it was pitched at 65°; for the heat and the attenuation go hand in hand.
A Dictionary of Arts, Manufactures and Mines Andrew Ure

She quite lacks the refinement, attenuation and imponderability you have achieved.
The Gay Gnani of Gingalee Florence Huntley

The symptoms here compiled were produced by the 3x attenuation and the tincture, using from one drop to thirty drops at a dose.
New, Old, and Forgotten Remedies: Papers by Many Writers Various

The secret of attenuation had thus become an open one to Pasteur.
Louis Pasteur Ren Vallery-Radot

Myers believes that in nearly every instance mutism follows stupor and is merely an attenuation of the latter process.
Benign Stupors August Hoch

The rush had quickened when she met his groan with an attenuation.
The Wings of the Dove, Volume II Henry James

noun
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
n.

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).

attenuation at·ten·u·a·tion (ə-těn’yōō-ā’shən)
n.

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.

The energy loss of an ultrasonic beam as it passes through a material.

communications
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].
(2003-07-29)