An officer of the papal court charged with the duty of registering and dating all documents issued by the Pope, and of representing the Pope in matters relating to grants, dispensations, etc. Compare datary.

A person who registers and dates a document. More generally: a chronologer; an expert in dates.

More fully "datary office", "datary court". A branch of the Apostolic Chancery charged with the dating of papal bulls and other documents.