nekulturan

1. rude; ill-mannered; uncultured
   Bilo je baš nekulturno da ga prekineš. — It was really rude of you to interrupt him.
   Vozač autobusa je bio nekulturan prema putnicima. — The bus driver was rude to the passengers.
2. uncultured; uneducated
   Nije on nekulturan, samo ne voli pozorište. — He isn't uncultured, he just doesn't like the theatre.

Most often refers to bad manners rather than lack of education.