perspicacious vs perspicacity

perspicacious is not a noun while perspicacity is a noun.

Word	Noun	Adjective	Verb	Adverb
perspicacious	No	Yes	No	No
perspicacity	Yes	No	No	No

perspicacious (noun)	perspicacity (noun)
	the capacity to assess situations or circumstances shrewdly and to draw sound conclusions
	intelligence manifested by being astute (as in business dealings)

perspicacious (adjective)	perspicacity (adjective)
mentally acute or penetratingly discerning
acutely insightful and wise