mute vs dumb

mute is a noun but dumb is not a noun.

Word	Noun	Adjective	Verb	Adverb
mute	Yes	Yes	Yes	No
dumb	No	Yes	No	No

As adjectives, mute and dumb are synonyms defined as:

Other synonyms of mute include silent.

mute (noun)	dumb (noun)
a device used to soften the tone of a musical instrument
a deaf person who is unable to speak

mute (adjective)	dumb (adjective)
expressed without speech	slow to learn or understand; lacking intellectual acuity
unable to speak because of hereditary deafness	unable to speak because of hereditary deafness
	temporarily incapable of speaking
	lacking the power of human speech

mute (verb)	dumb (verb)
deaden (a sound or noise), especially by wrapping