furl vs reef

furl is not a noun while reef is a noun.

Word	Noun	Adjective	Verb	Adverb
furl	No	No	Yes	No
reef	Yes	No	Yes	No

As verbs, reef is a hyponym of furl; that is, reef is a word with a more specific, narrower meaning than furl:

Other hyponyms of furl include douse, bolt, gather in, take in, brail.

furl (noun)	reef (noun)
	one of several strips across a sail that can be taken in or rolled up to lessen the area of the sail that is exposed to the wind
	a submerged ridge of rock or coral near the surface of the water

furl (verb)	reef (verb)
form into a cylinder by rolling	roll up (a portion of a sail) in order to reduce its area
	reduce (a sail) by taking in a reef
	lower and bring partially inboard