Olympus Mons Large volcano on Mars, the largest known volcano in the solar system. It consists of a central structure that ascends about 13 mi (21 km) above Mars’ s mean radius and is 335 mi (540 km) wide at the base; it is surrounded by an outward-facing cliff rising as much 6 mi (10 km) above the surrounding area. At the summit is a crater 53 mi (85 km) in diameter. For comparison. Earth’s largest volcano, Mauna Loa, is 75 mi (120 km) wide at the base and rises 5.6 mi (9 km) above the ocean floor.
Olynthus \o-'lin-thos\ Ancient Greek city, on the Chalcidice Peninsula, northeastern Greece. From the late 5th century bc it was the head of a strong confederacy of Greek towns known as the Chalcidian League. It was destroyed by Philip II in 348 bc. Excavations have revealed the grid plan of the ancient town and provided material for studying the relation¬ ship between Classical and Hellenistic Greek art.
om \'om\ In Hinduism and other Indian religions, a sacred syllable con¬ sidered the greatest of all mantras. The syllable om is composed of the three sounds a-u-m (in the Sanskrit language, the vowels a and u join to become o ), which represent three important triads: earth, atmosphere, and heaven; the major Hindu gods, Brahma, Vishnu, and Shiva; and the sacred Vedic scriptures, Rig, Yajur, and Sama (see Vedic religion). Thus om mys¬ tically embodies the essence of the universe. It is uttered at the beginning and end of Hindu prayers, chants, and meditation and is also freely used in Buddhist and Jain rituals.
Omagh Vo-ma\ District (pop., 2001: 47,735) and town (pop., 1991: 18,000), Northern Ireland. Formerly in County Tyrone, the district was established in 1973. The area was ruled by the ancient O’Neill family (5th-16th centuries), passing to English rule after the flight of Hugh O’Neill in 1607. It was the site of sectarian violence in 1998, when a car bomb killed 29 people. Most of the land is grazed by dairy cattle or sheep, and the rivers contain salmon and trout. Omagh town, the district seat, is a market and light-manufacturing centre.
Omaha Vo-ms-.ho, , o-mo- 1 ha\ City (pop., 2000: 390,007), eastern Nebraska, U.S., on the Missouri River, north of its junction with the Platte River. The city’s name, meaning “upstream people,” referred to the Omaha Indians. Omaha was founded in 1854 and incorporated as a city in 1857. In 1863 it became the starting point for the Union Pacific Rail¬ road Co.’s first transcontinental railroad and soon grew into a centre of trade and industry. The largest city in the state, it is a major livestock and grain market, as well as a railroad, meat-packing, and insurance centre. It is home to the University of Nebraska and the Joslyn Art Museum.
O'Mahony, John (b. 1816, near Mitchelstown, County Cork, Ire.—d. Feb. 6, 1877, New York, N.Y., U.S.) Irish-American founder of the U.S. branch of the Fenian Brotherhood (see Fenian movement), an Irish secret revolutionary society. An Irish resistance leader, he fled to New York in 1853, where he founded and led (1858-66) the Fenians. By 1865 the American Fenian group had become large and prosperous and was send¬ ing money and arms to Ireland. O’Mahony reluctantly backed the Irish Fenians’ decision to stage military raids in Canada against the British, part of a scheme to hold Canada hostage for the cause of Irish freedom. The raids failed and he resigned, but he was later called out of retirement (1872-77). See also John O'Neill.
Oman \o-'man\ officially Sultanate of Oman formerly Muscat and Oman Country, Middle East, southwestern Asia. It is on the south¬ east coast of the Arabian Peninsula. Area: 119,500 sq mi (309,500 sq km).
QATAR
® Doha
Abu Dhabi^
Tropic of Cancer
tl
UNITED ARAB EMIRATES
L*
Khasab MUSANDAM jr V PENINSULA!—
' I Gy
Shinas
y, . # §uhar ' Om Qn
AI-BuraymT®) V ^ Khabura
-&—
/ Mount* -Y^
’ —■ 1 Al-Akhdar ...• - ^ /? Ra’s
-V fio&n. Kidd
Masqat
*Qurayyat
SAUDI
ARABIA
AL WAHlBAH DUNES
AL-HARASlS PLAIN Kn U qm
MASlRAH
: -*" /Sawqirah
j Ba y
L Than)irTt # ' ^ v^KhurTya MurTya Bay
YEMEN -
RakhyQt* ?alilah ISLANDS
Cape Darbat ‘AIT
ARABIAN
SEA
"© 2002 Encyclopaedia Britannica, Inc.
Population (2005 est.): 2,409,000. Capitaclass="underline"
Muscat. The Omanis are predominantly Arab and tribal in organization. There are also many migrant workers from South Asia and eastern Africa who reside there.
Languages: Arabic (official), others. Religions: Islam (official); also Hin¬ duism, Christianity. Currency: Omani rial. Oman is a hot, arid country with high humidity along the coast. The Hajar Mountains parallel the shore of the Gulf of Oman, reaching an elevation of more than 10,000 ft (3,000 m). A broad expanse of sandy desert covers much of the country. Oman has a developing mixed economy, and the production and export of petroleum is its largest sector. It is a hereditary monarchy, with an advisory council; its head of state and government is the sultan. Human habitation dates to about the 3rd millennium bc. The Omani tribal system dates to Arab migration during the 2nd century ad. It was ruled by imams (Muslim religious lead¬ ers) of the Ibad! sect from the early Islamic period (mid-8th century) until the 12th century, when local rule was established. The Portuguese con¬ trolled the coastal areas c. 1507-1650, when they were expelled. The Al Bu SaTd, a dynasty founded in the mid-18th century, still rules Oman. The kingdom expanded into eastern Africa in the 18th- 19th century, where its capital was at Zanzibar. Oil was discovered in 1964. In 1970 the sultan was
© 2006 Encyclopaedia Britannica, Inc.
1408 I Oman ► Ondcicitje
deposed by his son, who began a policy of modernization, and under him Oman joined the Arab League and the United Nations. In the First Persian Gulf War, Oman cooperated with the forces allied against Iraq. It subse¬ quently continued to expand its foreign relations.
Oman, Gulf of Northwestern arm of the Arabian Sea, between the eastern part of the Arabian Peninsula and Iran. It is about 230 mi (370 km) wide and 340 mi (545 km) long and connects with the Persian Gulf through the Strait of Hormuz. It is the only entrance to the Persian Gulf from the Arabian Sea and Indian Ocean and is important as a shipping route for the oil-producing area around the Persian Gulf.
Omar, Mosque of See Dome of the Rock
Omar Khayyam \ I o- I mar- 1 k!- , yam\ byname of Ghiydth al-DTn Abu al-Fath ‘Umar ibn Ibrahim al-Neyshaburl al-Khayyaml (b. May 18, 1048, Neyshabur, Khorasan—d. Dec. 4, 1131, Neyshabur) Persian poet, mathematician, and astronomer. Educated in the sciences and philosophy, he was renowned in his country and time for his scientific achievements, but few of his prose writings survive. His verses attracted little attention until his roba l Tyat (“quatrains”) were loosely translated into English by Edward FitzGerald and published in 1859. Many of the quatrains (each of which was intended as an indepen¬ dent poem) are of doubtful attribution; most scholars agree on the authen¬ ticity of about 50, with controversy over some 200 others.
ombudsman Vam-.budz-msnV Swedish representative Represen¬ tative assigned by a large organization or a government to investigate citi¬ zen complaints and suggest solutions. An ombudsman’s office was established by the Swedish constitution of 1809. The idea soon spread to other Scandinavian countries and later to New Zealand, Britain, Germany, Israel, and some states or provinces in the U.S., Australia, and Canada. An ombudsman’s responsibility is to receive and investigate complaints and to serve as an independent and impartial arbiter in recommending what may be done to satisfy the complainant or in explaining why no action is necessary. Ombudsmen are now used in universities, corpora¬ tions, municipalities, and institutions such as hospitals.