Final answer:
An agreement that is enforceable by law is known as a contract, which is foundational to enabling transactions and economic growth, as it provides individuals with security and legal recourse.
Step-by-step explanation:
An agreement enforceable by law is known as a contract. This is because contractual rights are founded on property rights, allowing individuals to enter into agreements with others regarding the use of their property with the assurance of legal recourse in the event of noncompliance. For example, in an employment contract, a surgeon expects to be compensated for their provided services, and the non-payment would be seen as theft of property. In a society with a reliable legal system, contracts enable economic growth as they provide security that the terms and conditions of agreements will be fulfilled.