Monsignor (often rendered Monseigneur in Canadian English practice), is an ecclesiastical honorific used by certain priests and bishops of the Roman Catholic Church. It comes from the French mon seigneur, meaning "my lord." It is abbreviated Mons. or Msgr.

Monsignor is the simple title for bishops and archbishops, as opposed to their formal title of Excellency. In speaking, a simple "Monsignor" will suffice, while in the greeting portion of a letter, "Most Reverend Monsignor" is used.

Many priests also use the title monsignor. These priests use the title because they are honorary members of the Pontifical Family, appointed by the Pope himself. These members of the Pontifical Family hold their honor during the lifetime of the appointing Pope. Once a sede vacante occurs, they can no longer use the title monsignor.

Though there were more degrees in former times, the motu proprio of Paul VI entitled Pontificalis domus eliminated most of them. There are now just three ranks of honorary members of the Pontifical Family:

• Apostolic Prothonotaries (the highest and least common form)
• Honorary Prelates of His Holiness (formerly "Domestic Prelate")
• Chaplains of His Holiness (formerly "Papal Chamberlain")

A priest of one of the three ranks is addressed as "Monsignor" and is greeted and styled in writing as "Reverend Monsignor". Traditionally Papal Chamberlains were "Very Reverend" and the higher degrees "Right Reverend".

There are actually two kinds of Apostolic Prothonotaries: numerary and supernumerary. The difference between the two is that numerary Apostolic Prothonotaries have a distinctive dress and have the privilege of using certain vestments belonging to a bishop at Mass under certain conditions.

If they do not themselves possess the episcopal character, vicars general and episcopal vicars may also use the title monsignor. While many of them were made honorary members of the Pontifical Family during their career, their office includes the privileges formerly accorded to a third kind of Apostolic Prothonotary. While this third prothonotary was suppressed, the privileges granted to Vicars General ex officio were not. Vicars General make use of the title while they hold their office in the same manner as the honorary Pontifical Family members above.

References

• Heim, Bruno Bernard. Heraldry in the Catholic Church: Its Origins, Customs, and Laws. New Jersey: Humanities Pres Inc, 1978. ISBN 0-391-00873-0.
• Paul VI. "On the Papal Household." On the Papal Household, Reform of the Use of Pontifical Insignia, Simplification of Pontifical Rites and Insignia. Washington, DC: United States Catholic Conference, 1968.
• "Instruction on the dress, titles and coat-of-arms of cardinals, bishops and lesser prelates." L'Osservatore Romano, English ed. 17 Apr. 1969: 4. ISSN 0391-668X. Online at http://www.fiu.edu/~mirandas/instruction69.htm