sexual activity vs knocker

sexual activity and knocker both are nouns.

Word	Noun	Adjective	Verb	Adverb
sexual activity	Yes	No	No	No
knocker	Yes	No	No	No

sexual activity (noun)	knocker (noun)
activities associated with sexual intercourse	a device (usually metal and ornamental) attached by a hinge to a door
	either of two soft fleshy milk-secreting glandular organs on the chest of a woman
	one who disparages or belittles the worth of something
	a person who knocks (as seeking to gain admittance)
	(Yiddish) a big shot who knows it and acts that way; a boastful immoderate person