Decrease and Attenuation

noun

• A change downward.
  • usage: "there was a decrease in his temperature as the fever subsided"; "there was a sharp drop-off in sales"
  • synonyms: lessening, drop-off
• A process of becoming smaller or shorter.
  • synonyms: decrement
• The amount by which something decreases.
  • synonyms: decrement
• The act of decreasing or reducing something.
  • synonyms: diminution, reduction, step-down

verb

• Decrease in size, extent, or range.
  • usage: "The amount of homework decreased towards the end of the semester"; "The cabin pressure fell dramatically"; "her weight fell to under a hundred pounds"; "his voice fell to a whisper"
  • synonyms: diminish, lessen, fall
• Make smaller.
  • usage: "He decreased his staff"
  • synonyms: lessen, minify

• (v.t.) To cause to grow less; to diminish gradually; as, extravagance decreases one's means.
• (v.) A becoming less; gradual diminution; decay; as, a decrease of revenue or of strength.
• (n.) To grow less, -- opposed to increase; to be diminished gradually, in size, degree, number, duration, etc. or in strength, quality or excellence; as, they days decrease in length from June to December.
• (v.) The wane of the moon.

noun

• Weakening in force or intensity.
  • usage: "attenuation in the volume of the sound"
  • synonyms: fading
• The property of something that has been weakened or reduced in thickness or density. .

• (n.) The act of attenuating; the act of making thin or less dense or of rarefying, as fluids or gases.
• (n.) The act or process of making slender or the state of being slender; emaciation.
• (n.) The process of weakening in intensity; diminution of virulence; as, the attenuation of virus.

Attenuation is the fractional part of reduced energy or lost power due to smoothing or filtering.

(DoD, NATO) In mine warfare, the reduction in intensity of an influence as distance from the source increases.
(DoD, NATO) In camouflage and concealment, the process of making an object or surface less conspicuous by reducing its contrast to the surroundings and/or background. Also called tone down.
(DoD, NATO) Decrease in intensity of a signal, beam, or wave as a result of absorption of energy and of scattering out of the path of a detector, but not including the reduction due to geometric spreading, i.e., the inverse square of distance effect.