A more thorough explanation:

Definition: Falsity of consideration in Roman law. This might result from several things, such as a mistaken reason for making a gift or bequest.

Example: If someone gives a gift to another person because they believe that person is their long-lost relative, but it turns out that they are not related at all, then the gift was made under a falsa causa.

This example illustrates how a mistaken reason or motive can lead to a falsa causa. The person who gave the gift did so based on a false belief, which means that the consideration for the gift was false. In Roman law, this would render the gift invalid.