come down vs lower

come down is not a noun while lower is a noun.

Word	Noun	Adjective	Verb	Adverb
come down	No	No	Yes	No
lower	Yes	Yes	Yes	No

come down (noun)	lower (noun)
	the lower of two berths

come down (adjective)	lower (adjective)
	the bottom one of two

come down (verb)	lower (verb)
get sick	make lower or quieter
be the essential element	set lower
criticize or reprimand harshly	cause to drop or sink
move downward and lower, but not necessarily all the way	move something or somebody to a lower position
fall from clouds	look angry or sullen, wrinkle one's forehead, as if to signal disapproval