What term describes a formal agreement between two or more parties that is enforceable by law?

A formal agreement between two or more parties that is enforceable by law is best described as a contract. A contract establishes the rights and obligations of the parties involved and typically includes key elements such as offer, acceptance, consideration, and the intention to create legal relations. This enforceability is what distinguishes contracts from other types of agreements or informal arrangements.

While purchase orders and lease agreements can be forms of contracts, they are more specific in nature and depend on the general definition of a contract for their validity. A memorandum, on the other hand, is often a note or record of an understanding between parties and does not have the same legal enforceability as a formal contract. Therefore, the broad and fundamental nature of a contract as a legally binding agreement makes it the correct choice in this context.