limit vs knife-edge

limit and knife-edge both are nouns.

Word	Noun	Adjective	Verb	Adverb
limit	Yes	No	Yes	No
knife-edge	Yes	No	No	No

As nouns, knife-edge is a hyponym of limit; that is, knife-edge is a word with a more specific, narrower meaning than limit:

limit (noun)	knife-edge (noun)
the greatest possible degree of something	a narrow boundary
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

limit (verb)	knife-edge (verb)
restrict or confine within limits
place limits on (extent or amount or access)
decide upon or fix definitely