Legally binding is a term used to describe an agreement, document, or contract that is enforceable by law. Synonyms for legally binding include valid, enforceable, authoritative, binding, and conclusive. These terms all refer to the same concept: an agreement that is recognized and enforceable under the law. Other synonyms for legally binding include mandatory, obligatory, and compulsory. These words emphasize the requirement for compliance with the terms of an agreement. Ultimately, whether an agreement is legally binding depends on the specific laws and regulations that govern it. However, using synonyms for legally binding can help to clarify the importance and enforceability of an agreement.