illiterate vs unlettered

illiterate is a noun but unlettered is not a noun.

Word	Noun	Adjective	Verb	Adverb
illiterate	Yes	Yes	No	No
unlettered	No	Yes	No	No

illiterate (noun)	unlettered (noun)
a person unable to read

illiterate (adjective)	unlettered (adjective)
not able to read or write	having little acquaintance with writing
lacking culture, especially in language and literature	uneducated in general; lacking knowledge or sophistication
uneducated in the fundamentals of a given art or branch of learning; lacking knowledge of a specific field