The Collaborative International Dictionary of English v.0.48:

Saturate \Sat"u*rate\, v. t. [imp. & p. p. Saturated; p. pr. &
   vb. n. Saturating.] [L. saturatus, p. p. of saturare to
   saturate, fr. satur full of food, sated. See Satire.]
   1. To cause to become completely penetrated, impregnated, or
      soaked; to fill fully; to sate.
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            Innumerable flocks and herds covered that vast
            expanse of emerald meadow saturated with the
            moisture of the Atlantic.             --Macaulay.
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            Fill and saturate each kind
            With good according to its mind.      --Emerson.
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   2. (Chem.) To satisfy the affinity of; to cause to become
      inert by chemical combination with all that it can hold;
      as, to saturate phosphorus with chlorine.
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The Collaborative International Dictionary of English v.0.48:

Saturated \Sat"u*ra`ted\, a.
   1. Filled to repletion; holding by absorption, or in
      solution, all that is possible; as, saturated garments; a
      saturated solution of salt.
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   2. (Chem.) Having its affinity satisfied; combined with all
      it can hold; -- said of certain atoms, radicals, or
      compounds; thus, methane is a saturated compound.
      Contrasted with unsaturated.
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   Note: A saturated compound may exchange certain ingredients
         for others, but can not take on more without such
         exchange.
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   Saturated color (Optics), a color not diluted with white; a
      pure unmixed color, like those of the spectrum.
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WordNet (r) 3.0 (2006):

saturated
    adj 1: being the most concentrated solution possible at a given
           temperature; unable to dissolve still more of a
           substance; "a saturated solution" [syn: saturated,
           concentrated] [ant: unsaturated]
    2: used especially of organic compounds; having all available
       valence bonds filled; "saturated fats" [ant: unsaturated]
    3: (of color) being chromatically pure; not diluted with white
       or grey or black [syn: saturated, pure] [ant:
       unsaturated]