Unmannerly refers to behavior that is impolite, discourteous, and disrespectful. To describe this behavior, there are several synonyms that can be used, including rude, disrespectful, ill-mannered, discourteous, impolite, brusque, curt, insolent, and uncivil. Each of these words describes behavior that goes against the accepted norms of polite conduct. Additionally, synonyms like boorish, churlish, and uncouth emphasize the lack of refinement in a person's behavior. Overall, these synonyms provide ample options for describing behavior that is unmannerly and help convey the appropriate degree of disapproval and criticism for such actions.