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.

Decomposed \De`com*posed"\, a. (Zo["o]l.)
   Separated or broken up; -- said of the crest of birds when
   the feathers are divergent.

Source : WordNet®

decomposed
     adj : broken down or disintegrated by rot; "a badly decomposed
           body"