A more thorough explanation:

Definition: Retractus feudalis is a legal term used in Scots law. It refers to a superior's right to pay off a debt owed by a vassal in exchange for the return of the conveyance of the vassal's lands.

Example: Let's say that John is a vassal who owes a debt to his superior, Jane. In order to pay off the debt, John offers to sell his land to Jane. However, Jane has the right of retractus feudalis, which means that she can pay off John's debt and take back the conveyance of the land instead of buying it from him.

This legal concept was used in feudal times to ensure that the superior had control over the lands and could prevent them from falling into the wrong hands. It also allowed the superior to protect their interests by paying off any debts owed by their vassals.