dual vs plural

dual is not a noun while plural is a noun.

Word	Noun	Adjective	Verb	Adverb
dual	No	Yes	No	No
plural	Yes	Yes	No	No

dual (noun)	plural (noun)
	the form of a word that is used to denote more than one

dual (adjective)	plural (adjective)
consisting of or involving two parts or components usually in pairs	grammatical number category referring to two or more items or units
a grammatical number category referring to two items or units as opposed to one item (singular) or more than two items (plural)	composed of more than one member, set, or kind
having more than one decidedly dissimilar aspects or qualities