authority vs unsure

authority is a noun but unsure is not a noun.

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

authority (noun)	unsure (noun)
the power or right to give orders or make decisions
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)	unsure (adjective)
	lacking or indicating lack of confidence or assurance
	lacking self-confidence