The Collaborative International Dictionary of English v.0.48:

Saturation \Sat`u*ra"tion\, n. [L. saturatio: cf. F.
   saturation.]
   1. The act of saturating, or the state of being saturating;
      complete penetration or impregnation.
      [1913 Webster]

   2. (Chem.) The act, process, or result of saturating a
      substance, or of combining it to its fullest extent.
      [1913 Webster]

   3. (Optics) Freedom from mixture or dilution with white;
      purity; -- said of colors.
      [1913 Webster]

   Note: The degree of saturation of a color is its relative
         purity, or freedom from admixture with white.
         [1913 Webster]

WordNet (r) 3.0 (2006):

saturation
    n 1: the process of totally saturating something with a
         substance; "the impregnation of wood with preservative";
         "the saturation of cotton with ether" [syn: impregnation,
         saturation]
    2: the act of soaking thoroughly with a liquid
    3: a condition in which a quantity no longer responds to some
       external influence
    4: chromatic purity: freedom from dilution with white and hence
       vivid in hue [syn: saturation, chroma, intensity,
       vividness]

Moby Thesaurus II by Grady Ward, 1.0:

97 Moby Thesaurus words for "saturation":
   Munsell chroma, Technicolor, amplitude, bellyful, brewing,
   bright color, brightness, brilliance, chroma, chromatic color,
   chromaticity, color, color quality, colorfulness,
   colorimetric quality, congestion, cool color, decoction, drench,
   drenching, ducking, dunking, engorgement, fill, flood tide, full,
   fullness, gaiety, glut, gorgeousness, high tide, high water, hue,
   hyperemia, imbruement, imbuement, impletion, impregnation,
   infiltration, infusion, injection, instillation, instillment,
   intensity, interpenetration, leaching, lightness, lixiviation,
   maceration, marination, more than enough, neutral color,
   overbrimming, overburden, overcharge, overflow, overfreight,
   overfullness, overload, overspill, overweight, penetration,
   percolation, permeation, pervasion, plenitude, plethora, pulping,
   pure color, purity, repletion, richness, satiation, satiety,
   satisfaction, saturatedness, saturation point, seething, skinful,
   snootful, soak, soakage, soaking, sopping, souse, sousing,
   spring tide, steeping, suffusion, supersaturation, surcharge,
   surfeit, tint, tone, value, vividness, warm color



The Free On-line Dictionary of Computing (30 December 2018):

saturation

   1.  In colour theory, the "colourfulness" of a
   stimulus relative to its brightness, the amount of the
   dominant wavelength relative to other wavelengths in the
   colour, one of the three coordinates in the hue, saturation,
   value (HSV) and hue, saturation, brightness (HSB) colour
   models.

   White, black and grey contain equal amounts of red, green and
   blue light and are completely unsaturated.  A pure colour with
   very little gray in it is highly saturated.  The amount of
   saturation does not affect the hue of a colour and is
   unrelated to the value (total amount of light in a colour).

   There are several competing mathematical definitions of
   saturation.


(http://www.ncsu.edu/scivis/lessons/colormodels/color_models2.html#saturation).


(http://www.pomona.edu/academics/courserelated/classprojects/visual-lit/saturation/saturation.html).

   2. The state of any system that is operating at its maximum
   capacity, e.g. a network connection that is carry a continuous
   stream of data with no idle time.  Capacity planning aims to
   monitor load and increase resources before saturation is
   reached.

   (2008-05-09)