loosen vs fluff

loosen is not a noun while fluff is a noun.

Word	Noun	Adjective	Verb	Adverb
loosen	No	No	Yes	No
fluff	Yes	No	Yes	No

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

Other hyponyms of loosen include scarify, ruffle.

loosen (noun)	fluff (noun)
	a blunder (especially an actor's forgetting the lines)
	something of little value or significance
	any light downy material

loosen (verb)	fluff (verb)
become loose or looser or less tight	ruffle (one's hair) by combing the ends towards the scalp, for a full effect
make loose or looser	erect or fluff up
make less dense	make a mess of, destroy or ruin
disentangle and raise the fibers of
cause to become loose
become less severe or strict
make less severe or strict