diminution vs diminish

diminution is a noun but diminish is not a noun.

Word	Noun	Adjective	Verb	Adverb
diminution	Yes	No	No	No
diminish	No	No	Yes	No

diminution (noun)	diminish (noun)
the act of decreasing or reducing something
the statement of a theme in notes of lesser duration (usually half the length of the original)
change toward something smaller or lower

diminution (verb)	diminish (verb)
	decrease in size, extent, or range
	lessen the authority, dignity, or reputation of