crumble vs decay

crumble is not a noun while decay is a noun.

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

As verbs, crumble and decay are synonyms defined as:

Other synonyms of crumble include dilapidate.

crumble (noun)	decay (noun)
	the organic phenomenon of rotting
	a gradual decrease; as of stored charge or current
	the process of gradually becoming inferior
	the spontaneous disintegration of a radioactive substance along with the emission of ionizing radiation
	an inferior state resulting from the process of decaying

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