The Collaborative International Dictionary of English v.0.48:

Pigment \Pig"ment\, n. [L. pigmentum, fr. the root of pingere to
   paint: cf. F. pigment. See Paint, and cf. Pimento,
   Orpiment.]
   1. Any material from which a dye, a paint, or the like, may
      be prepared; particularly, the refined and purified
      coloring matter ready for mixing with an appropriate
      vehicle.
      [1913 Webster]

   2. (Physiol.) Any one of the colored substances found in
      animal and vegetable tissues and fluids, as bilirubin,
      urobilin, chlorophyll, etc.
      [1913 Webster]

   3. Wine flavored with species and honey. --Sir W. Scott.
      [1913 Webster]

   Pigment cell (Physiol.), a small cell containing coloring
      matter, as the pigmented epithelial cells of the choroid
      and iris, or the pigmented connective tissue cells in the
      skin of fishes, reptiles, etc.
      [1913 Webster] Pigmental

WordNet (r) 3.0 (2006):

pigment
    n 1: dry coloring material (especially a powder to be mixed with
         a liquid to produce paint, etc.)
    2: any substance whose presence in plant or animal tissues
       produces a characteristic color
    3: a substance used as a coating to protect or decorate a
       surface (especially a mixture of pigment suspended in a
       liquid); dries to form a hard coating; "artists use `paint'
       and `pigment' interchangeably" [syn: paint, pigment]
    v 1: acquire pigment; become colored or imbued
    2: color or dye with a pigment; "pigment a photograph"