untouchable vs impure

untouchable is a noun but impure is not a noun.

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

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

untouchable (adjective)	impure (adjective)
forbidden to the touch	(used of persons or behaviors) immoral or obscene
impossible to assail	combined with extraneous elements
beyond the reach of criticism or attack or impeachment	having a physical or moral blemish so as to make impure according to dietary or ceremonial laws
not capable of being obtained
(especially used in traditional Hindu belief of the lowest caste or castes) defiling