| OSI | Osmium | Oslo |
| Osteichthyes | OS/2 | OS/360 |
| OstrogothThis article deals with the continental Ostrogoths. For information on the Ostrogoths that Jordanes placed in Scandinavia, see Ostrogothia, Scandza and Geats. The Ostrogoths (often problematically denoted "Eastern Goths", as opposed to "West Goths", Visig | OsteoporosisOsteoporosis is a disease of bone in which the amount of bone is decreased and the strength of trabecular bone is reduced, cortical bone becomes thin and bones are susceptible to fracture. It is defined according to the bone mineral density (BMD) as measu | Osama bin LadenUsmah bin Muhammad bin `Awad bin Ldin (born March 10, 1957 or July 30, 1957) ( Arabic: ), commonly known as Osama bin Laden , is the head of al-Qaida, a militant Islamist organization that has been involved in terrorist attacks against civilians and milit |
| OsmosisOsmosis is the diffusion of a solvent through a semipermeable membrane from a region of low solute concentration to a region of high solute concentration. The semipermeable membrane is permeable to the solvent, but not to the solute, resulting in a chemic | Osman IOsman I ( 1258 1326) was the founder of the Ottoman Empire. He was born in 1258 and got the title bey (chief) from his father, Ertoğrul, as the ruler of the village of Soğut in 1281. The birth of the empire originated with the conquest of the | Osman IIOsman II ( November 3, 1604 May 20, 1622) was the Sultan of the Ottoman Empire from 1618 until his death. Osman was the son of Ahmed I. He ascended the throne at the early age of 14 as the result of a coup d'etat against his uncle Mustafa I. Despite his y |
| OstaraOstara is one of the eight solar holidays or sabbats of Neopaganism. It is celebrated on the spring equinox, in the northern hemisphere circa March 21 and in the southern hemisphere circa September 23. The name may refer to an ancient Germanic goddess nam | Oscar PetersonOscar Emmanuel Peterson is a Canadian jazz pianist and composer. He was born on August 15, 1925 in Montreal, Quebec, Canada,. He began learning trumpet and piano from his father at the age of five, but by the age of seven, after a bout of tuberculosis, he | OscillationSee Oscillator (disambiguation) for particular types of oscillation and oscillators. Oscillation is the periodic variation, typically in time, of some measure as seen, for example, in a swinging pendulum. The term vibration is sometimes used more narrowly |
| Ostrich | OSGi | Oswald Spengler |
| Oscar Wilde | Ostracism | Oscar |
| Ossian | OSS | OSI model |
| Oscar Hammerstein II | Osiris | Ostwald process |
| Oswald of Northumbria | Oskar Schindler | Oscar I of Sweden |
| OS-9 | OS/390 | Oscilloscope |
| Ossip Zadkine | Osama | Oscar Niemeyer |
| Ostia | Oswald Avery | Osco |
| Osvaldo Ardiles | Osaka, Osaka | Oswego County, New York |
| Ostiaks | Osage-orange | Oscar class submarine |
| Ostpolitik | Oscar E. Berninghaus | Ossë |
| Óscar Romero | Osip Mandelstam | Osmium tetroxide |
| Oswald Mosley | Oswald the Lucky Rabbit | Oscar the Grouch |
| Oslo Accords | Oscoda, Michigan | Oswald von Wolkenstein |
| Osceola County, Florida | Osteopathy | Osborne House |
| Ossicles | Oswiu of Northumbria | Oscar (fish) |
| Osage County, Oklahoma | Osterley | Osage County, Missouri |
| Oscoda County, Michigan | Osceola County, Michigan | Oscar De La Hoya |
| Osborne County, Kansas | Osage County, Kansas | Osceola County, Iowa |
| Ostholstein | Osiraq | Oshun |
| Oshunmare | Oss | Oscan |
| Oscar II of Sweden | Oscarville, Alaska | Osceola, Arkansas |
| Osprey, Florida | Osburn, Idaho | Oswego, Illinois |
| Osgood, Indiana | Osceola, Indiana | Ossian, Indiana |
| Osceola, Iowa | Osterdock, Iowa | Oskaloosa, Iowa |
| Osage, Iowa | Ossian, Iowa | Oskaloosa, Kansas |
| Oswego, Kansas | Osawatomie, Kansas | Osage City, Kansas |
| Osborne, Kansas | Osborn, Maine | Ossineke, Michigan |
| Ossineke Township, Michigan | Osceola Township, Houghton County, Michigan | Oscoda Township, Michigan |
| Oshtemo Township, Michigan | Osceola Township, Osceola County, Michigan | Osage Township, Minnesota |
| Osakis Township, Minnesota | Ostrander, Minnesota | Osseo, Minnesota |
| Oslo, Minnesota | Oshawa Township, Minnesota | Oscar Township, Minnesota |
| Osborne Township, Minnesota | Osceola Township, Minnesota | Oshkosh Township, Minnesota |
| Osyka, Mississippi | Osceola, Missouri | Osgood, Missouri |
| Oshkosh, Nebraska | Osmond, Nebraska | Osceola, Nebraska |