sexual activity vs put down

sexual activity is a noun but put down is not a noun.

Word	Noun	Adjective	Verb	Adverb
sexual activity	Yes	No	No	No
put down	No	No	Yes	No

sexual activity (noun)	put down (noun)
activities associated with sexual intercourse

sexual activity (verb)	put down (verb)
	put down in writing; of texts, musical compositions, etc.
	make a record of; set down in permanent form
	put in a horizontal position
	remove (cargo, people, etc.) from and leave
	cause to sit or seat or be in a settled position or place
	put (an animal) to death
	reduce in worth or character, usually verbally
	cause to come to the ground