OLYMPIA, a plain in a valley in Elis, on the Peloponnesus, traversed by the river Alpheus, and in which the Olympic Games were celebrated every fifth year in honour of Zeus, and adorned with temples (one to Zeus and another to Hera), statues, and public buildings.

OLYMPIAD, a name given to the period of four years between one celebration of the Olympic Games and another, the first recorded dating from July 776 B.C.

OLYMPIAS, the wife of Philip II. of Macedonia, and mother of Alexander the Great; divorced by Philip, who married another, she fled to Epirus, and instigated the assassination of Philip and the execution of her rival; returned to Macedonia on the accession of her son, who always treated her with respect, but allowed her no part in public affairs; on his death she dethroned his successor, but driven to bay in her defence afterwards, she was compelled to surrender the power she had assumed, and was put to death 316 B.C.

OLYMPIC GAMES, were originally open only to competitors of pure Hellenic descent, and the reward of the victors was but a wreath of wild olive, though to this their fellow-citizens added more substantial honours; they consisted of foot and chariot races, and feats of strength as well as dexterity.  See OLYMPIA.

OLYMPUS, a mountain range in Greece, between Thessaly and Macedonia, the highest peak of which is 9750 ft.; the summit of it was the fabled abode of the Greek gods; it is clothed with forests of pine and other trees.

OLNEY, a little town in Buckinghamshire, associated with the life of Cowper, and where he wrote, along with John Newton, the “Olney Hymns.”

OM, a mystic word among the Hindus and Buddhists; presumed to be latent with some magic virtue, and used on solemn occasions as a sort of spiritual charm efficacious with the upper powers, and potent to draw down divine assistance in an hour of need.

OMAGH (4), on the Strule, 34 m.  S. of Londonderry; is the county town of Tyrone; though a very ancient town it has been rebuilt since 1743, when it was destroyed by fire; it is the head-quarters of the NW. military district.

OMAHA (102), chief city of Nebraska, on the W. bank of the Missouri, 20 m. above the confluence of the Platte; is connected by a bridge with Council Bluffs on the opposite shore; it has many fine buildings, including colleges and schools; its silver-smelting works are the largest in the world; it ranks third in the pork-packing industry, and has besides manufactures of linseed oil, boilers, and safes; an important railway centre, it lies midway between the termini of the Union Pacific Railroad; near it are the military head-quarters of the Platte department.

OMAN, a territory of Arabia, lying along the shores of the Persian Gulf and the Arabian Sea, round the south-eastern nob of the peninsula; has some stretches of very fertile country where there happens to be water for irrigation, but the coast is very hot and not healthy.  The region is subject to the Sultan of Muscat, who is in turn a pensioner of the Anglo-Indian Government.