authority vs plural

authority and plural both are nouns.

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

authority (noun)	plural (noun)
the power or right to give orders or make decisions	the form of a word that is used to denote more than one
official permission or approval
freedom from doubt; belief in yourself and your abilities
an authoritative written work
an administrative unit of government
an expert whose views are taken as definitive
(usually plural) persons who exercise (administrative) control over others

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