(Latin: abbreviare, to shorten)

The use of a single letter for the entire word, or a sign or mark for a word or phrase, a custom common from early days, especially in Greece and Rome, and adopted by Christians first as a means of keeping their secrets from enemies and then as a matter of economy in transcribing manuscripts. The abbreviations used by the Papal Chancery, the theological schools of Paris and Oxford, and the Bologna school of civillaw became from the ninth century the standards for Europe. They abound in manuscripts of Roman and canon law, theology, civiland ecclesiastical documents, and chronicles. The invention of printing greatly influenced the use of abbreviations.

Ecclesiastical abbreviations are:

Well-known examples of abbreviations are:

The various titles of religious orders, priests, and congregations have each their abbreviations, e.g., O.P., Ordo Prredicatorum, Order of Preachers. Abbreviations in general ecclesiastical use and in titles of religious orders are given in their proper alphabetical places.