decay vs erode

decay is a noun but erode is not a noun.

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

As verbs, erode is a hyponym of decay; that is, erode is a word with a more specific, narrower meaning than decay:

decay (noun)	erode (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

decay (verb)	erode (verb)
fall into decay or ruin	remove soil or rock
lose a stored charge, magnetic flux, or current	become ground down or deteriorate
undergo decay or decomposition