decomposition vs decay

decomposition and decay both are nouns.

Word	Noun	Adjective	Verb	Adverb
decomposition	Yes	No	No	No
decay	Yes	No	Yes	No

As nouns, decomposition and decay are synonyms defined as:

As nouns, decay is a hypernym of decomposition; that is, decay is a word with a broader meaning than decomposition:

decomposition: (biology) the process of decay caused by bacterial or fungal action
decay: the process of gradually becoming inferior

As nouns, decay is a hypernym of decomposition; that is, decay is a word with a broader meaning than decomposition:

decomposition (noun)	decay (noun)
the analysis of a vector field	the organic phenomenon of rotting
the organic phenomenon of rotting	a gradual decrease; as of stored charge or current
(biology) the process of decay caused by bacterial or fungal action	the process of gradually becoming inferior
(chemistry) separation of a substance into two or more substances that may differ from each other and from the original substance	the spontaneous disintegration of a radioactive substance along with the emission of ionizing radiation
in a decomposed state	an inferior state resulting from the process of decaying

decomposition (verb)	decay (verb)
	fall into decay or ruin
	lose a stored charge, magnetic flux, or current
	undergo decay or decomposition