sex vs libidinous

sex is a noun but libidinous is not a noun.

Word	Noun	Adjective	Verb	Adverb
sex	Yes	No	Yes	No
libidinous	No	Yes	No	No

sex (noun)	libidinous (noun)
activities associated with sexual intercourse
the properties that distinguish organisms on the basis of their reproductive roles
all of the feelings resulting from the urge to gratify sexual impulses
either of the two categories (male or female) into which most organisms are divided

sex (adjective)	libidinous (adjective)
	driven by lust; preoccupied with or exhibiting lustful desires

sex (verb)	libidinous (verb)
tell the sex (of young chickens)
to evoke sexual feelings