untouchable vs unclean

untouchable is a noun but unclean is not a noun.

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

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

untouchable (adjective)	unclean (adjective)
forbidden to the touch	having a physical or moral blemish so as to make impure according to dietary or ceremonial laws
impossible to assail	soiled or likely to soil with dirt or grime
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