civil law. An agreement by which a person appointed to his creditor, a certain day, or a certain time, at which he promised to pay; or it maybe defined, simply. an agreement by which a person promises a creditor to pay him. 2. When a person by this pact promises his own creditor to pay him, there arises a new obligation which does not destroy the former by which he was already bound, but which is accessory to it; and by this multiplicity of obligations the right of the creditor is strengthened.