The word "tashmitum" comes from ancient Mesopotamia and refers to a particular type of contract or agreement. While there are not many direct synonyms for this specific term, there are related words and phrases that could be used in its place. For example, one could use the term "covenant," which also implies a binding agreement between two parties. Additionally, terms like "pact," "deal," or "treaty" could be used to convey similar ideas. In modern legal contexts, phrases like "contractual obligation" or "binding agreement" might be more appropriate. Overall, while there may not be a one-to-one synonym for "tashmitum," there are certainly many ways to convey the same idea in English.