In Roman law. A special constitution by which the Roman emperor conferred on some single person some anomalous or irregular right, or imposed upon some single person some anomalous or irregular obligation, or inflicted on some single person some anomalous or irregular punishment. When such privilegia conferred anomalous rights, they were styled “favorable.” When they imposed anomalous obligations, or inflicted anomalous punishments, they were styled “odious.” Aust Jur.