The Collaborative International Dictionary of English v.0.48:

Decomposition \De*com`po*si"tion\, n. [Pref. de- (in sense 3
   intensive) + composition: cf. F. d['e]composition. Cf.
   Decomposition.]
   1. The act or process of resolving the constituent parts of a
      compound body or substance into its elementary parts;
      separation into constituent part; analysis; the decay or
      dissolution consequent on the removal or alteration of
      some of the ingredients of a compound; disintegration; as,
      the decomposition of wood, rocks, etc.
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   2. The state of being reduced into original elements.
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   3. Repeated composition; a combination of compounds. [Obs.]
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   Decomposition of forces. Same as Resolution of forces,
      under Resolution.

   Decomposition of light, the division of light into the
      prismatic colors.
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