castaway vs untouchable

castaway and untouchable both are nouns.

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

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

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

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

castaway (adjective)	untouchable (adjective)
	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