Civil law. The person who assumes the payment of a debtor's obligation, thus releasing the original debtor upon the creditor's acceptance of the new debtor. By this term is understood the person who alone becomes bound for the debt of another, whether the latter were obligated or not. He differs from a surety, who is bound together with his principal. The name given in the civil law to a person who undertook the debt of another, by which the original debtor was freed from his obligation in so far as regarded the original creditor. See Delegatio.