inaccessible vs untouchable

inaccessible is not a noun while untouchable is a noun.

Word	Noun	Adjective	Verb	Adverb
inaccessible	No	Yes	No	No
untouchable	Yes	Yes	No	No

As adjectives, inaccessible and untouchable are synonyms defined as:

Other synonyms of inaccessible include unobtainable, unprocurable.

inaccessible (noun)	untouchable (noun)
	belongs to lowest social and ritual class in India

inaccessible (adjective)	untouchable (adjective)
capable of being reached only with great difficulty or not at all	forbidden to the touch
not capable of being obtained	impossible to assail
	beyond the reach of criticism or attack or impeachment
	not capable of being obtained
	(especially used in traditional Hindu belief of the lowest caste or castes) defiling