When a business deal or agreement is "under negotiation", it means that the parties involved are in the process of discussing and trying to come to an agreement. There are several synonyms that can be used in its place like "in talks", "in discussion", "in conversation", "in deliberation" and "in bargaining". Each synonym can convey slightly different meanings. For example, "in talks" might imply a more informal or exploratory process, while "in bargaining" suggests a more contentious negotiation with each party pushing for their own interests. Regardless of the term used, negotiations can be challenging, and it's important to remain patient and remember that compromise is key to reaching a successful agreement.