Source : Webster's Revised Unabridged Dictionary (1913)

Decompose \De`com*pose"\, v. t. [imp. & p. p. {Decomposed}; p.
   pr. & vb. n. {Decomposing}.] [Cf. F. d['e]composer. Cf.
   {Discompose}.]
   To separate the constituent parts of; to resolve into
   original elements; to set free from previously existing forms
   of chemical combination; to bring to dissolution; to rot or
   decay.

Decompose \De`com*pose"\, v. i.
   To become resolved or returned from existing combinations; to
   undergo dissolution; to decay; to rot.

Source : WordNet®

decompose
     v 1: separate (substances) into constituent elements or parts
          [syn: {break up}, {break down}]
     2: lose a stored charge, magnetic flux, or current; "the
        particles disintegrated during the nuclear fission
        process" [syn: {disintegrate}, {decay}]
     3: break down; "The bodies decomposed in the heat" [syn: {rot},
         {molder}, {moulder}]