Decomposition

[Couch Potatoe]

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.

[Little_Girl]

the action of decaying, or causing something to decay:

[Magaret]

The state or process of rotting; decay.