There are a myriad of synonyms for the word "a deal" that range from casual to formal, colloquial to academic. For instance, "an agreement" is a more formal way to refer to a deal, while "bargain" can imply a beneficial agreement for both parties or something obtained at a lower cost. Other options include "transaction," "pact," "treaty," and "contract." In social contexts, "arrangement," "understanding," or "accord" could be more fitting. Whether negotiating a business deal or outlining an arrangement with a friend, having a variety of synonyms at your disposal can add variety and clarity to your language skills.