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, France and Oxford, England, and the Bologna. Italy school of civil law became from the ninth century the standards for Europe. They abound in manuscripts of Roman and canon law, theology, civil and ecclesiastical documents, and chronicles. The invention of printing greatly influenced the use of abbreviations.

Ecclesiastical abbreviations are

  • administrative, as used in pontifical documents, once numerous, but all abolished by Pope Leo XIII in 1878, except for the names of sees, forms of address, and titles of Roman Congregations and individual ecclesiastical authorities
  • liturgical, as in the description of or directions for liturgical acts
  • scholastic, as for academic titles and degrees
  • chronological, for the civil or ecclesiastical year

Well-known examples of abbreviations are:

  • A.D., Anno Domini, Year of the Lord
  • A.M.D.G., Ad Majorem Dei Gloriam, For the greater glory of God
  • B.C., Before Christ
  • I.H.S., usually interpreted Jesus Hominum Salvator, Jesus Saviour of Men
  • R.I.P., Requiescat in Pace, May he (or she) rest in peace.

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.