Underbred in a sentence as an adjective

They plainly did not know how to treat me, but behaved like persons who are underbred.

Many make a large fortune, who remain underbred and pathetically stupid to the last.

Underbred definitions

adjective

(of persons) lacking in refinement or grace

See also: ill-bred bounderish lowbred rude yokelish

adjective

of inferior or mixed breed; "an underbred dog"