A more thorough explanation:

Definition: Mutui datio is a Latin term used in Roman law. It refers to the lending of objects that can be weighed, measured, or counted, such as bullion, corn, wine, oil, and coined money. The borrower is expected to repay by restoring an equal amount of the object borrowed.

Example: A person borrows 10 ounces of gold from a lender. The borrower is expected to return 10 ounces of gold to the lender at a later date. This is an example of mutui datio.

Mutui datio is different from a sale or exchange because the borrower is expected to return the exact same object that was borrowed. It is also different from a loan for use, where the borrower is expected to return the object in the same condition it was borrowed. Mutui datio is a real contract in which the borrower is strictly liable to return an equivalent amount of the object borrowed.