Frederick Oakeley

 O Antiphons

 Oates's Plot

 Oaths

 English Post-Reformation Oaths

 Archdiocese of Oaxaca

 Monastery of Obazine

 Obba

 Obedience

 Religious Obedience

 Obedientiaries

 Oblate Sisters of Providence

 Oblates of Mary Immaculate

 Oblates of Saint Francis de Sales

 Oblati

 Obligation

 Tighernach O'Braein

 Obregonians

 Obreption

 Terence Albert O'Brien

 David O'Bruadair

 Edmund Bailey O'Callaghan

 Torlogh O'Carolan

 Occasionalism

 Occasions of Sin

 Thomas Occleve

 Occult Art, Occultism

 Occurrence

 Vicariate Apostolic of Central Oceania

 Daniel O'Connell

 Charles O'Conor (1)

 Charles O'Conor (2)

 Octavarium Romanum

 Octave

 Gelasius O'Cullenan

 Eugene O'Curry

 Daniel O'Daly

 Donogh Mór O'Daly

 Carlo Odescalchi

 O Deus Ego Amo Te

 Cornelius O'Devany

 St. Odilia

 St. Odilo

 John Mary Odin

 Walter Odington

 St. Odo

 St. Odo (Oda)

 Odo

 Edmund O'Donnell

 John O'Donovan

 Bl. Odo of Cambrai

 Odo of Canterbury

 Odo of Cheriton

 Odo of Glanfeuil

 John O'Dugan

 Joseph O'Dwyer

 Johann Œcolampadius

 Episcopal œconomus

 Œcumenius

 John James Maximilian Oertel

 Oettingen

 Offa

 Offerings

 Offertory

 Divine Office

 Office of the Dead

 Maurice O'Fihely

 O Filii et Filiæ

 Diocese of Ogdensburg

 Marco D'Oggione

 Ven. John Ogilvie

 Diocese of Ogliastra

 Eugene O'Growney

 John O'Hagan

 Thomas O'Hagan

 John O'Hanlon

 Theodore O'Hara

 Patrick O'Hely

 Thomas O'Herlahy

 Ambrose Bernard O'Higgins

 Ohio

 Aloys Karl Ohler

 Dermod O'Hurley

 Maelbrighte O'Hussey

 Oil of Saints

 Ointment in Scripture

 Alonso de Ojeda

 Jean d'Okeghem

 Oklahoma

 St. Olaf Haraldson

 Nicolaus Oláh

 Olba

 Old Catholics

 Old Chapter

 Ven. Edward Oldcorne

 Oldenburg

 Old Hall (St. Edmund's College)

 Hugh Oldham

 Augustino Oldoini

 Arthur O'Leary

 Olenus

 Zbigniew Olesnicki

 Jean-Jacques Olier

 Diocese of Olinda

 Oliva

 Gian Paolo Oliva

 Pierre Olivaint

 George Oliver

 Mount Olivet

 Olivetans

 Pierre Jean Olivi

 Olivier de la Marche

 Léon Ollé-Laprune

 Archdiocese of Olmütz

 Michael O'Loghlen

 St. Olympias

 Olympus

 Diocese of Omaha

 Ombus

 Kathleen O'Meara

 St. Omer

 Omission

 Omnipotence

 Hugh O'Neill

 Owen Roe O'Neill

 Onias

 Ontario

 Ontologism

 Ontology

 Shrine of Oostacker

 Ophir

 Diocese of Oporto

 Gilles-Marie Oppenordt

 Diocese of Oppido Mamertina

 St. Optatus

 Optimism

 Right of Option

 Malachias O'Queely

 Oracle

 Diocese of Oran

 Councils of Orange

 Orange Free State

 Vicariate Apostolic of Orange River

 Orans

 Orate Fratres

 Oratorio

 Oratory

 Oratory of Saint Philip Neri

 Nicolas d'Orbellis

 Orcagna

 Orcistus

 Ordeals

 Ordericus Vitalis

 Holy Orders

 Ordinariate

 Ordinary

 Ordines Romani

 Oregon

 Archdiocese of Oregon City

 Bernard O'Reilly

 Edmund O'Reilly (1)

 Edmund O'Reilly (2)

 Hugh O'Reilly

 John Boyle O'Reilly

 Myles William Patrick O'Reilly

 Oremus

 Diocese of Orense

 Nicole Oresme

 Organ

 Diocese of Oria

 Barnaba Oriani

 Oriental Study and Research

 Orientation of Churches

 Orientius

 Oriflamme

 Origen and Origenism

 Original Sin

 Diocese of Orihuela

 St. Joseph Oriol

 Diocese of Oristano

 Orkneys

 Niccolò Orlandini

 Councils of Orléans

 Diocese of Orléans

 Barent Van Orley

 Philibert de l'Orme

 Oropus

 Patrick Henry O'Rorke

 Paulus Orosius

 Orphans and Orphanages

 Giuseppe Agostino Orsi

 Orsini

 Orsisius

 Abraham Ortelius

 Orthodox Church

 Orthodoxy

 Feast of Orthodoxy

 Orthosias

 Ortolano Ferrarese

 Orval

 Diocese of Orvieto

 Matthieu Ory

 Diocese of Osaka

 O Salutaris Hostia

 Osbald

 Ven. Edward Osbaldeston

 Osbern

 Oscott (St. Mary's College)

 Osee

 Diocese of Osimo

 Diocese of Osma

 St. Osmund

 Diocese of Osnabrück

 Arnaud d'Ossat

 Diocese of Ossory

 Ostensorium

 Suburbicarian Diocese of Ostia and Velletri

 Ostiensis

 Ostracine

 Christian Ostraka

 Ostrogoths

 Philip O'Sullivan Beare

 St. Oswald (1)

 St. Oswald (2)

 St. Oswin

 Otfried of Weissenburg

 Othlo

 St. Othmar

 Marcus Salvius Otho

 Archdiocese of Otranto

 Archdiocese of Ottawa

 University of Ottawa

 St. Otto

 Otto I, the Great

 Otto II

 Otto III

 Otto IV

 Ottobeuren

 Otto of Freising

 Otto of Passau

 Otto of St. Blasien

 St. Ouen

 Feast of Our Lady, Help of Christians

 Feast of Our Lady of Good Counsel

 Brothers of Our Lady of the Fields

 Feast of Our Lady of the Snow

 Friedrich Overbeck

 Bernhard Heinrich Overberg

 Diocese of Oviedo

 Nicholas Owen

 John Oxenford

 Henry Nutcombe Oxenham

 Oxford

 University of Oxford

 Oxford Movement (1833-1845)

 Oxyrynchus

 Antoine-Frédéric Ozanam

 Jacques Ozanam

 Ozias

Tighernach O'Braein


Irish annalist and Abbot of Roscommon and Clonmacnoise, died 1088. Little is known of his personal history except that he must have been born in the early part of the eleventh century and that he came from a Connaught family. His "Annals" (among the earliest of Irish annals) are of the greatest value to the historian of Ireland because of the author's attempt to synchronize Irish events with those of the rest of Europe from the earliest times to his own day. His learning is shown by his quotations, among others, from the works of the Venerable Bede, Josephus, Eusebius, and Orosius, not to speak of the Vulgate. But his sources for the Irish portions of the "Annals" are not now discoverable because of the loss of the Irish manuscripts from which he drew his information. Only fragments of Tighernach's "Annals" are now extant; these are in a vellum of the twelfth century and one of the fourteenth century in the Bodleian Library, Oxford, and in a fourteenth-century manuscript in Trinity College Library (Dublin). These fragments were published by Dr. O'Conor in his "Rerum Hibernicarum Scriptores" (1825), but O'Conor's text is full of errors. They have recently been published and translated by Whitley Stokes in the "Revue Celtique" (vols. XVI, XVII, XVIII). Two pages in facsimile are given in Gilbert's "National Manuscripts of Ireland", part I.

JOSEPH DUNN