half-clothed vs underclothed

half-clothed and underclothed both are adjectives.

Word	Noun	Adjective	Verb	Adverb
half-clothed	No	Yes	No	No
underclothed	No	Yes	No	No

As adjectives, half-clothed and underclothed are synonyms defined as:

Other synonyms of half-clothed include scantily clad.

half-clothed (adjective)	underclothed (adjective)
inadequately clothed	inadequately clothed