outcast vs untouchable

outcast and untouchable both are nouns.

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

As nouns, untouchable is a hyponym of outcast; that is, untouchable is a word with a more specific, narrower meaning than outcast:

Other hyponyms of outcast include heretic, misbeliever, religious outcast, leper, Harijan.

outcast (noun)	untouchable (noun)
a person who is rejected (from society or home)	belongs to lowest social and ritual class in India

outcast (adjective)	untouchable (adjective)
excluded from a society	forbidden to the touch
	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