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.

Source : WordNet®

decomposing
     adj : becoming rotten; "a field covered with thousands of
           decomposing bodies"; "John Brown's body lies
           a-moldering in the grave" [syn: {moldering}, {mouldering}]