Referendary is a number of administrative positions, of various rank, in chanceries and other official organisations in Europe.
The office of referendarius (plural: referendarii, from the Latin refero, "I inform") existed at the Byzantine Court. Such officials reported to the Emperor on the memorials of petitioners, and conveyed to the judges the Emperor's orders in connection with such memorials.
During the Frankish Empire's Merovingian period, the official who would later be known as the chancellor (cancellarius) was termed the referendarius. See also Royal Administration of Merovingian and Carolingian Dynasties.
Other medieval kingdoms also had a referendary, e.g., Anianus, who in 506 CE compiled the Breviary of Alaric for that king of the Visigoths.
Later the office proliferated and thus became devalued, as reflected in compound titles differentiating some such offices, e.g., in the Polish-Lithuanian Commonwealth. In later iterations of the Polish state, the title occurred again, e.g., as "referendary of state."
A referendary can also be an official (Grand Chancellor) in an order of knighthood, e.g. the Order of Saint Lazarus.
In the Papal Curia Romana (court), the office of referendarius apostolicus ('apostolic referendary') originated in the Middle Ages; their duty was to receive all petitions directed to the Holy See, to report on them to the pope and to tender him advice. The treatment and decision varied according to the nature of the question: if a favour was concerned, it might be either granted or refused; if some dispute, the pope decided whether it should be referred to a judge. The referendarii were entrusted with all arrangements for these papal decisions, which they had to prepare for the pope's signature (signatura).