keep down vs limit

keep down is not a noun while limit is a noun.

Word	Noun	Adjective	Verb	Adverb
keep down	No	No	Yes	No
limit	Yes	No	Yes	No

As verbs, limit is a hypernym of keep down; that is, limit is a word with a broader meaning than keep down:

Other hypernyms of keep down include circumscribe, confine to.

keep down (noun)	limit (noun)
	the greatest possible degree of something
	the boundary of a specific area
	as far as something can go
	the greatest amount of something that is possible or allowed
	the mathematical value toward which a function goes as the independent variable approaches infinity
	final or latest limiting point

keep down (verb)	limit (verb)
manage not to throw up	restrict or confine within limits
place a limit on the number of	place limits on (extent or amount or access)
put down by force or intimidation	decide upon or fix definitely