1.  attenuation(n = noun.event) fading - weakening in force or intensity; "attenuation in the volume of the sound"
is a kind of weakening
Derived form verb attenuate₂

2.  attenuation(n = noun.attribute) - the property of something that has been weakened or reduced in thickness or density;
is a kind of weakness
Derived form verb attenuate₁

1.  The act or process of making slender, or the state of being slender; emaciation. [1913 Webster]

2.  The act of attenuating; the act of making thin or less dense, or of rarefying, as fluids or gases. [1913 Webster]

3.  The process of weakening in intensity; diminution of virulence; as, the attenuation of virus. [1913 Webster]

N  contraction, reduction, diminution, decrease of size, defalcation, decrement, lessening, shrinking, compaction, tabes, collapse, emaciation, attenuation, tabefaction, consumption, marasmus, atrophy, systole, neck, hourglass, condensation, compression, compactness, compendium, squeezing, strangulation, corrugation, astringency, astringents, sclerotics, contractility, compressibility, coarctation, inferiority in size, contracting, astringent, shrunk, contracted, strangulated, tabid, wizened, stunted, waning, neap, compact, unexpanded &c (expand), contractile, compressible, smaller &c (small).

N  powderiness, pulverulence, sandiness, efflorescence, friability, powder, dust, sand, shingle, sawdust, grit, meal, bran, flour, farina, rice, paddy, spore, sporule, crumb, seed, grain, particle, limature, filings, debris, detritus, tailings, talus slope, scobs, magistery, fine powder, flocculi, smoke, cloud of dust, cloud of sand, cloud of smoke, puff of smoke, volume of smoke, sand storm, dust storm, pulverization, comminution, attenuation, granulation, disintegration, subaction, contusion, trituration, levigation, abrasion, detrition, multure, limitation, tripsis, filing, mill, arrastra, gristmill, grater, rasp, file, mortar and pestle, nutmeg grater, teeth, grinder, grindstone, kern, quern, koniology, powdery, pulverulent, granular, mealy, floury, farinaceous, branny, furfuraceous, flocculent, dusty, sandy, sabulous, psammous, arenose, arenarious, arenaceous, gritty, efflorescent, impalpable, lentiginous, lepidote, sabuline, sporaceous, sporous, pulverizable, friable, crumbly, shivery, pulverized, attrite, in pieces.