[Oberon], the king of the fairies, and the husband of Titania.
[Obi], a river and, with its tributaries, great water highway of West Siberia, which rises in the Altai Mountains, and after a course of 2120 m. falls into the Arctic Ocean.
[Objective], a philosophical term used to denote that which is true universally apart from all merely private sense or judgment, and finds response in the universal reason, the reason that is common to all rational beings; it is opposed to subjective, or agreeable to one's mere feelings or fancy.
[Oblates], the name given to an organisation of secular priests living in community, founded by St. Charles Borromeo at the end of the 16th century, and who are ready to render any services the bishop may require of them.
[Oboe], a treble-sounding musical instrument of the reed class, to which the bassoon is reckoned the bass.
[Obelus], a small coin worth about a penny, according to a custom among the Greeks placed in the mouth of a corpse at burial to pay to Charon to ferry the ghost of it over the Styx.
[O'Brien, William], journalist, and a Nationalist ex-M.P. for Cork; was twice over imprisoned for political offences; had to retire in 1895; b. 1852.
[O'Brien, William Smith], Irish patriot; entered Parliament in 1826; sat for Limerick from 1835 to 1843, when he joined the Repeal Association under O'Connell, but separated from it; joined the physical force Young Ireland party, and became the head; attempted an insurrection, which failed, and involved him in prosecution for treason and banishment for life; a free pardon was afterwards granted on promise of abstaining from all further disloyalty; he died at Bangor, in North Wales (1803-1864).
[Obscurantist], name given to an opponent to modern enlightenment as professed by the devotees of modern science and philosophy.
[Obsidian], a hard, dark-coloured rock of a glassy structure found in lava, which breaks with conchoidal fracture.