put down vs sex activity

put down is not a noun while sex activity is a noun.

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

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

put down (verb)	sex activity (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