sex vs extramarital sex

sex and extramarital sex both are nouns.

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

sex (noun)	extramarital sex (noun)
activities associated with sexual intercourse	sexual intercourse between individuals who are not married to one another
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 (verb)	extramarital sex (verb)
tell the sex (of young chickens)
to evoke sexual feelings