behind vs sex activity

behind and sex activity both are nouns.

Word	Noun	Adjective	Verb	Adverb
behind	Yes	Yes	No	Yes
sex activity	Yes	No	No	No

behind (noun)	sex activity (noun)
the fleshy part of the human body that you sit on	activities associated with sexual intercourse

behind (adjective)	sex activity (adjective)
having the lower score or lagging position in a contest

behind (adverb)	sex activity (adverb)
in or to or toward the rear
remaining in a place or condition that has been left or departed from
in debt
in or into an inferior position
showing a time that is earlier than the actual time