Being formal in communication means adhering to proper etiquette and conventions. Synonyms for "be formal" include acting decorously, being polished, using proper language, and presenting oneself professionally. It also means abiding by social customs, observing professional protocols, maintaining a formal tone, and dressing in formal attire. Communication styles vary for different occasions, and being formal is appropriate for diplomatic engagements, formal business meetings, and formal events. Being formal doesn't mean being stuffy or distant, but approaching conversations and interactions in a cognizant and courteous manner. Overall, using synonyms for "be formal" are a great way to add more elegance and delicacy to your communication.