Main Entry: de·com·po·si·tion Pronunciation: (")dE-"käm-p&-'zish-&n Function: noun : the act or process ofdecomposing : the state of being decomposed: a: the separation or resolution (as of a substance) into constituent parts or elements or into simpler compounds<decomposition of mercuric oxide into mercury and oxygen> b: organic decay decomposition of a dead body>