plural vs parallel bars

plural and parallel bars both are nouns.

Word	Noun	Adjective	Verb	Adverb
plural	Yes	Yes	No	No
parallel bars	Yes	No	No	No

plural (noun)	parallel bars (noun)
the form of a word that is used to denote more than one	gymnastic apparatus consisting of two parallel wooden rods supported on uprights

plural (adjective)	parallel bars (adjective)
grammatical number category referring to two or more items or units
composed of more than one member, set, or kind