many vs multiplicity

many is not a noun while multiplicity is a noun.

Word	Noun	Adjective	Verb	Adverb
many	No	Yes	No	No
multiplicity	Yes	No	No	No

many (noun)	multiplicity (noun)
	a large number
	the property of being multiple

many (adjective)	multiplicity (adjective)
a quantifier that can be used with count nouns and is often preceded by `as' or `too' or `so' or `that'; amounting to a large but indefinite number; quantifier, plural pronoun; quantifier, plural