What does "saturation" mean?

Saturation: (Chem.) The act, process, or result of saturating a substance, or of combining it to its fullest extent.

Additional senses

  1. 2.(Optics) Freedom from mixture or dilution with white; purity; -- said of colors. Note: The degree of saturation of a color is its relative purity, or freedom from admixture with white.

Sources