sex activity vs missionary position

sex activity and missionary position both are nouns.

Word	Noun	Adjective	Verb	Adverb
sex activity	Yes	No	No	No
missionary position	Yes	No	No	No

sex activity (noun)	missionary position (noun)
activities associated with sexual intercourse	a position for sexual intercourse; a man and woman lie facing each other with the man on top; so-called because missionaries thought it the proper position for primitive peoples