underbred vs ill-bred

underbred and ill-bred both are adjectives.

Word	Noun	Adjective	Verb	Adverb
underbred	No	Yes	No	No
ill-bred	No	Yes	No	No

As adjectives, underbred and ill-bred are synonyms defined as:

Other synonyms of underbred include bounderish, lowbred, rude, yokelish.

underbred (adjective)	ill-bred (adjective)
of inferior or mixed breed	(of persons) lacking in refinement or grace
(of persons) lacking in refinement or grace