WordNet sense 1 (in a decomposed state):

disintegration

WordNet sense 2 ((chemistry) separation of a substance into two or more substances that may differ from each other and from the original substance):

chemical decomposition reaction, decomposition reaction

WordNet sense 3 ((biology) the process of decay caused by bacterial or fungal action):

putrefaction, rot, rotting

WordNet sense 4 (the organic phenomenon of rotting):

decay

WordNet sense 5 (the analysis of a vector field):

vector decomposition