A more thorough explanation:

Definition: Nudum pactum (Latin for "bare agreement") is a contract that is not legally enforceable because it lacks consideration, which is the exchange of something of value between the parties involved.

Example: If John promises to give Jane $100 for no reason, and Jane agrees to the promise, this is a nudum pactum because there is no consideration exchanged between them. If John fails to give Jane the $100, she cannot legally enforce the promise because there was no consideration.

Explanation: In order for a contract to be legally enforceable, there must be consideration exchanged between the parties involved. Consideration is something of value that is given or promised in exchange for something else. In the example given, John promised to give Jane $100 for no reason, which means there was no consideration exchanged. Therefore, this is a nudum pactum and cannot be legally enforced.