Co-recursive is a relatively specialized term that refers to a programming concept. It involves multiple functions that call upon one another in a cyclical manner. However, since co-recursive is a field-specific term, there are not many synonyms for it. A few alternative terms that could be used in some contexts are mutual recursion, cyclical recursion, and interdependent recursion. These synonyms all capture the idea of a cycle of functions that call on one another. While they may not be as precise as co-recursive, they could be used to convey similar ideas in certain contexts. Nonetheless, co-recursive is the most common and accurate term used in programming and computer science to describe this process.