undressed vs unattired

undressed and unattired both are adjectives.

Word	Noun	Adjective	Verb	Adverb
undressed	No	Yes	No	No
unattired	No	Yes	No	No

As adjectives, undressed and unattired are synonyms defined as:

Other synonyms of undressed include unappareled, unclad, ungarbed, ungarmented.

undressed (adjective)	unattired (adjective)
having removed clothing	having removed clothing
of lumber or stone or hides; not finished or dressed