suppress vs muffle

suppress is not a noun while muffle is a noun.

Word	Noun	Adjective	Verb	Adverb
suppress	No	No	Yes	No
muffle	Yes	No	Yes	No

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

suppress: consciously restrain from showing; of emotions, desires, impulses, or behavior
muffle: suppress in order to conceal or hide

Other hyponyms of suppress include dampen, stifle, repress, smother, stifle, strangle, choke.

suppress (noun)	muffle (noun)
	a kiln with an inner chamber for firing things at a low temperature

suppress (verb)	muffle (verb)
bring under control by force or authority	suppress in order to conceal or hide
lessen to the point of stopping	deaden (a sound or noise), especially by wrapping
put out of one's consciousness
consciously restrain from showing; of emotions, desires, impulses, or behavior
come down on or keep down by unjust use of one's authority