A more thorough explanation:

Term: Reliqua
Definition: Reliqua is a term used in civil law to refer to the remaining amount of a debt that is left unpaid after balancing or liquidating an account. It is the amount that is still owed by the debtor to the creditor.
Example: John owes $500 to his creditor. He pays $300, leaving a balance of $200. This $200 is the reliqua that John still owes to his creditor.
The example illustrates how reliqua is used in civil law to refer to the remaining amount of a debt that is left unpaid after partial payment.