A more thorough explanation:

Definition: Indebitum is a type of debt in Roman law that is not actually owed. If someone pays money for a debt that does not exist, they can recover that money through a legal action called condictio indebiti.

Example: If someone mistakenly pays a bill that they do not owe, they can use condictio indebiti to recover that money. For instance, if a person pays a utility bill for a property they no longer own, they can recover that payment as indebitum.