| Orthorhombic | Oroshi hocho | Organ stop |
| Order of SmileThe Order of Smile is awarded to adults distinguished in their love, care and aid for children. The award was established in 1968 by a Polish magazine Kurier Polski and it was officially recognized by the United Nations in 1979. Today the order is awarded | OrchalgiaOrchalgia is chronic pain of the testicles or scrotum that typically lasts for more than three months. Orchalgia may be caused by injury, surgery, cancer or testicular torsion. About one out of every 1,000 vasectomy patients are afflicted with orchalgia. | OrdovicesThe Ordovices were one of the Celtic tribes living in the British Islands, before the Roman invasion of Britain. Its tribal lands were located in Wales between the Silures to the south and the Deceangeli to the north. The Ordovices were conquered by the R |
| Ordered ringIn abstract algebra, an ordered ring is a ring that is a totally ordered set. Ordered rings are familiar from arithmetic. Examples include the integers, the rational numbers and the real numbers. The complex numbers do not form an ordered field. In analog | Orange, New South WalesOrange is a provincial city about 250 kilometres west of Sydney, the State capital of New South Wales, Australia. The population is approaching 40,000 and the city is a major provincial centre. Key industries include mining, health services and education. | OrthopnoeaOrthopnoea is breathing difficulty which occurs when lying flat. Orthopnoea is a symptom of heart failure. It can also occur in those with asthma and chronic bronchitis. |
| OrvalOrval monastery's is a Cistercian monastery founded in 1132 located in Belgium in the Gaume region. The monastery is well-known by its history and spiritual life but also for its local production of a trappist_beer and a specific trappist cheese. History | Oregon Supreme CourtThe Oregon Supreme Court is the highest state court in the Oregon judicial department (branch of government). The court has seven elected justices, each of whom serves a six-year term after winning a nonpartisan election. They choose one of their own to s | Orlando BoschOrlando Bosch is a Cuban exile accused of a variety of anti- Castro political violence (considered terrorist attacks by both the Cuban government and the FBI, although many such acts are sponsored by the CIA). Most notably he is accused of the October 6, |
| Orell Gessner Füssli | Ori | Orthomyxoviridae |
| Oriya alphabet | Orphanage (band) | Ormont-Dessous |
| Ormont-Dessus | Orpheus (role-playing game) | Orleans County |
| Oregon County | Oryx and Crake | ORF |
| Orange Juice | Orland Kurtenbach | Organisasi Papua Merdeka |
| Orodreth (Steward) | Orchestra hit | Oral consonant |
| Ordered partition of a set | Orange GGN | Orhei |
| Orb | Ore, Sussex | Order of the Star of India |
| Order of the Indian Empire | Order of the Crown of India | Oregon Ballot Measure 30 (2004) |
| Oregon Ballot Measure 36 (1996) | Oregon Ballot Measure 47 (1996) | Oregon tax revolt |
| Oregon Ballot Measure 50 (1997) | Orthodox Christian Mission Center | Origins of the American Civil War (1/4) |
| Ordeal of the Union | Organic production | Oregon Ballot Measure 51 (1997) |
| Orange Line (Washington Metro) | Order of the Golden Fleece | Organ of Corti |
| Oral culture | Orla Orbe | Oregon Public Broadcasting |
| Oral stage | Orestes | Orbit (anatomy) |
| Organised persecution of ethnic Germans | Oroch | Orbital Sciences X-34 |
| Origin (album) | Orthosie (moon) | Ornithischia |
| Ornithodira | Ordinary language philosophy | Orcas Island |
| Orallo | Orthophoto | Orie |
| Ornithogalum | Ornithogalum narbonense | Orkney Brewery |
| Orchestra Hall, Minneapolis | Orhan Veli | Orlando Villas Boas |
| Orloff | Origins of baseball | Oracle (comics) |
| Order of Our Lady of the Good Death | Oregon Bottle Bill | Ordos Desert |
| Ordos | Organizational structure | Oread Institute |
| Orange-breasted Green Pigeon | Oregon Geographic Names | Orange Pekoe |
| Orquesta tipica | Ormond, Victoria | Oranjestad, Sint Eustatius |
| Origin of replication | Origin of language | Orizare |
| Oro-Medonte, Ontario | Oregon Petition | Oregon congressional district |
| Orange-billed Babbler | Orange drink | Ortona Mare |
| Orbital engine | Oriole Warbler | Oracle Forms |
| Orr | ORACLE (Teletext) | Oriental Shorthair |
