Search by letter: O
Search by letter
Search by letter: O
- Ornamentation in Music: Decorative Notes, Historical Practice, and Performance Ornamentation (music)
- Orne (department) — Normandy department of France Orne
- Ornella Muti
- Ornette Coleman
- Ornex — commune in Ain, Auvergne-Rhône-Alpes, France Ornex
- Ornithischia — the bird‑hipped, beaked herbivorous dinosaurs Ornithischia
- Ornithocheirus: a crested pterosaur genus Ornithocheirus
- Ornitholestes: a small Late Jurassic coelurosaur Ornitholestes
- Ornithology: the scientific study of birds Ornithology
- Ornithomimidae: the ostrich-like theropods Ornithomimidae
- Ornithomimus
- Ornithopod dinosaurs: bird-hipped herbivores and their evolution Ornithopod
- Ornithurae
- Örnsköldsvik — Swedish coastal town in Västernorrland County Örnsköldsvik
- Örnsköldsvik Municipality
- Orny, Vaud — municipality in the Morges district of Switzerland Orny, Switzerland
- Orochimaru (Naruto) — Profile, Abilities, History, and Legacy Orochimaru (Naruto)
- Orodel (commune in Dolj County, Romania) Orodel
- Orofino, Idaho
- Orogeny: the geological process of mountain building Orogeny
- Oromia Region, Ethiopia Oromia
- Oron District (canton of Vaud, Switzerland) Oron (district)
- Oron-la-Ville — former municipality in Vaud, Switzerland Oron-la-Ville
- Oron-le-Châtel (former municipality in Vaud, Switzerland) Oron-le-Châtel
- Oron (Vaud) — Municipality in the Lavaux-Oron district Oron, Vaud
- Orono, Minnesota: lakeside suburb on Lake Minnetonka Orono, Minnesota
- Orontid dynasty (Eruandid / Yervanduni): rulers of ancient Armenia Orontid dynasty
- Oropharyngeal cancer: causes, diagnosis, treatment, and prevention Oropharyngeal cancer
- Orosei, Sardinia: coastal town and comune Orosei
- Orosirian Period (Palaeoproterozoic): 2.05–1.80 billion years ago Orosirian
- Orotelli — town and comune in the Province of Nuoro, Sardinia Orotelli
- Oroville East (Kelly Ridge), California Oroville East, California
- Oroville, California: Butte County Seat and Gateway to Lake Oroville Recreation Oroville, California
- Orp-Jauche: municipality in Walloon Brabant, Belgium Orp-Jauche
- Orphan: children without parental care Orphan
- Orphan Black: Canadian science fiction series exploring cloning and identity Orphan Black
- Orphanage
- Orphans of the Storm (1921): Griffith’s historical melodrama Orphans of the Storm
- Orpheus: legendary musician and figure of Greek myth Orpheus
- Orphism (ancient Greek religious movement) Orphism (religion)
- Orpiment (As2S3) — yellow arsenic sulfide mineral Orpiment
- Orpund — municipality in the Biel/Bienne district, Canton of Bern Orpund
- Orquesta Sinfónica Simón Bolívar
- Orrery: Mechanical models of the Solar System Orrery
- Orri Vigfússon — Icelandic conservationist and salmon-restoration leader Orri Vigfússon
- Orrin Hatch: Long-serving U.S. Senator and Conservative Lawmaker Orrin Hatch
- Orriule (commune in Pyrénées-Atlantiques, France) Orriule
- Orroli, Sardinia Orroli
- Orrorin tugenensis: an early hominin from the Tugen Hills Orrorin tugenensis
- Orsa — locality in Dalarna, Sweden Orsa
- Orsa Municipality (Orsa kommun) Orsa Municipality
- Orsanco
- Orsans (Aude) — Small commune in Occitanie, France Orsans, Aude
- Orschwihr, Haut-Rhin commune in Alsace Orschwihr
- Orselina — hillside municipality above Locarno in Ticino, Switzerland Orselina
- Orsières — Alpine municipality in Valais, Switzerland Orsières
- Orsinian Tales
- Orson Bean: American actor, comedian, and television personality Orson Bean
- Orson Scott Card: novelist, teacher, and public commentator Orson Scott Card
- Orson Welles: filmmaker, actor, playwright and radio innovator Orson Welles
- Ortac (islet near Alderney) Ortac
- Ortacesus, Sardinia — overview, geography, economy and culture Ortacesus
- Ortenaukreis — district in Baden-Württemberg, Germany Ortenaukreis
- Orthez — historic town in Béarn, Pyrénées-Atlantiques, France Orthez
- Orthodontist: dental specialist in teeth alignment and bite correction Orthodontist
- Orthodox: meaning, traditions, and distinctions Orthodox
- Orthodox Church of Ukraine
- Orthodox Judaism: Beliefs, Practices, History, and Community Life Orthodox Judaism
- Orthodoxy (right belief and institutional authority) Orthodoxy
- Orthogonal Frequency-Division Multiplexing (OFDM) Orthogonal frequency-division multiplexing
- Orthographic depth: how writing maps to speech Orthographic depth
- Orthographic projection
- Orthography: conventions and history of writing a language Orthography
- Orthomyxoviridae: family of segmented negative-strand RNA viruses Orthomyxoviridae
- Orthonectida — simple multicellular parasites of marine invertebrates Orthonectida
- Orthonormality in Inner Product Spaces Orthonormality
- Orthopedic cast: purpose, materials, application, care, and history Orthopedic cast
- Orthoptera: grasshoppers, crickets and katydids — biology and importance Orthoptera
- Orthosie (moon of Jupiter) Orthosie (moon)
- Orto botanico di Pisa — University of Pisa Botanical Garden Orto botanico di Pisa
- Orton, Eden (Cumbria) Orton
- Ortonville, Minnesota
- Ortueri — town and comune in Nuoro, Sardinia, Italy Ortueri
- Orunamamu: Mary Beth Washington — American-Canadian Storyteller and Teacher Orunamamu
- Orune (Orùne) — Town and comune in Sardinia, Italy Orune
- Oruro Department (Bolivia) Oruro Department
- Orust Municipality (Orusts kommun), Västra Götaland, Sweden Orust Municipality
- Orvault, commune in Loire-Atlantique, France Orvault
- Orvieto — hilltop city of Umbria with cathedral, wells and ancient roots Orvieto
- Orvieto Cathedral (Duomo di Orvieto) — Gothic masterpiece in Umbria Orvieto Cathedral
- Orville Redenbacher: American popcorn entrepreneur and agronomist Orville Redenbacher
- Sir Orville Turnquest — Bahamian statesman and former Governor‑General Orville Turnquest
- Orville, Pas-de-Calais (commune in northern France) Orville, Pas-de-Calais
- Orvin — municipality in the Jura bernois, Canton of Bern, Switzerland Orvin
- Oryx: antelopes adapted to deserts and dry grasslands Oryx
- Orzens (Vaud) — Municipality in Jura-Nord Vaudois, Switzerland Orzens
- OS X El Capitan (10.11) — Apple's performance‑focused macOS release OS X El Capitan
- OS X Mavericks (10.9) — Apple desktop operating system OS X Mavericks
- OS X Mountain Lion (10.8) — Apple’s 2012 Macintosh operating system OS X Mountain Lion
- OS X Yosemite (version 10.10) OS X Yosemite
- Os‑Marsillon (commune in Pyrénées‑Atlantiques, France) Os-Marsillon
- Osage County, Kansas county code OS
- Osage County, Missouri
- Osage County, Oklahoma
- Osage Nation: history, culture, and modern government Osage Nation
- Osage Plains: the Tallgrass Region of Missouri, Kansas, Oklahoma and Texas Osage Plains
- Osage River (Missouri) Osage River
- Osage, Iowa: county seat and regional community in north-central Iowa Osage, Iowa
- Osage, Oklahoma
- Osaka — Overview, History, Culture and Significance Osaka
- Osaka Castle: history, architecture, and cultural significance Osaka Castle
- Osaka Prefecture (Ōsaka-fu) Osaka Prefecture
- Ōsaka Station
- Osaka University: Japan’s comprehensive national research university Osaka University
- Osama bin Laden: founder of al‑Qaeda and central figure in global jihad Osama bin Laden
- Osamu Chiba (千葉 修) — Japanese footballer (born 1968) Osamu Chiba
- Osamu Dazai: life, works, and influence of a Japanese novelist Osamu Dazai
- Osamu Hirose (Japanese footballer, born 1965) Osamu Hirose
- Osamu Maeda (Japanese footballer, born 1965) Osamu Maeda
- Osamu Shimomura — Japanese chemist and co-discoverer of GFP Osamu Shimomura
- Osamu Taninaka — Japanese footballer and national team representative Osamu Taninaka
- Osamu Tezuka: life, work, and influence of a manga pioneer Osamu Tezuka
- Osamu Yamaji (Japanese footballer, born 1929) Osamu Yamaji
- Osasco, São Paulo — Brazilian municipality and urban center Osasco
- Osawatomie, Kansas
- Osborne County, Kansas — overview, geography, history, and communities Osborne County, Kansas
- Osborne House: Victorian Royal Residence on the Isle of Wight Osborne House
- Osborne, Kansas
- Osborne's Bull: Spain's Iconic Roadside Silhouette Osborne's bull
- Osburg — municipality near Trier in the Trier‑Saarburg district Osburg
- Osburn, Idaho — a Silver Valley city in Shoshone County Osburn, Idaho
- Osby, Sweden Osby
- Osby Municipality
- Oscar: award, given name, fish, and cultural uses Oscar
- Oscar (Astronotus ocellatus) — popular South American cichlid Oscar (fish)
- Óscar Arias — Costa Rican statesman and Nobel Peace Prize laureate Óscar Arias
- Oscar B. Cintas (1887–1957): Cuban industrialist, diplomat and collector Oscar B. Cintas
- Óscar Berger — President of Guatemala (2004–2008) Óscar Berger
- Óscar Chávez — Mexican singer-songwriter and actor Óscar Chávez
- Oscar De La Hoya: boxer, Olympic champion and boxing promoter Oscar De La Hoya
- Óscar de la Renta Oscar de la Renta
- Oscar Dronjak — Swedish guitarist and HammerFall founder Oscar Dronjak
- Oscar E. Huber (1917–2017) — South Dakota farmer, rancher and legislator Oscar E. Huber
- Óscar Enrique Sánchez (El Conejo) — Guatemalan footballer and coach Óscar Enrique Sánchez
- Oscar Fritschi — Swiss FDP Politician and Cantonal Leader (1939–2016) Oscar Fritschi
- Oscar Fulloné — Argentine footballer and international manager Oscar Fulloné
- Oscar Furlong: Argentine basketball champion and tennis coach Oscar Furlong
- Oscar Gamble
- Oscar Goodman
- Oscar Hammerstein II
- Oscar Hertwig: German Embryologist and Pioneer of Fertilization Research Oscar Hertwig
- Oscar Hijuelos
- Oscar Holderer
- Oscar I of Sweden and Norway (1799–1859) Oscar I of Sweden
- Oscar Isaac
- Óscar Julio Vian Morales
- Oscar Luigi Scalfaro: Italian President and Constitutional Figure (1918–2012) Oscar Luigi Scalfaro
- Oscar Malapitan — Filipino mayor and public official Oscar Malapitan
- Óscar Malbernat — Argentine footballer and manager Oscar Malbernat
- Óscar Marcelino Álvarez — Argentine footballer and expatriate player in Greece Óscar Marcelino Álvarez
- Oscar Martinez (The Office) — character profile and cultural significance Oscar Martinez (The Office)
- Oscar Micheaux: Pioneer of African‑American Independent Filmmaking Oscar Micheaux
- Oscar N. Harris — American accountant and North Carolina public servant Oscar N. Harris
- Oscar Niemeyer: Brazilian modernist architect known for sculptural concrete forms Oscar Niemeyer
- Oscar Núñez — Cuban‑American Actor and Comedian Oscar Nunez
- Óscar Pereiro
- Óscar Pérez (Venezuelan investigator and activist) Óscar Pérez
- Oscar Peterson: Canadian Jazz Pianist and Influential Performer Oscar Peterson
- Oscar Pettiford: Jazz Bassist, Cellist and Bebop Innovator Oscar Pettiford
- Oscar Pistorius: Athlete, Trial, and Public Legacy Oscar Pistorius
- Oscar Robertson
- Óscar Arnulfo Romero y Galdámez Óscar Romero
- Oscar Ruggeri — Argentine defender and World Cup winner Oscar Ruggeri
- Oscar Stanton De Priest: Chicago Representative and Civil Rights Pioneer Oscar Stanton De Priest
- Oscar Taveras: Dominican–Canadian Major League outfielder Oscar Taveras
- Oscar the Grouch: Sesame Street's Cantankerous Muppet Oscar the Grouch
- Óscar Ustari — Argentine goalkeeper and international squad player Oscar Ustari
- Oscar von Sydow (Swedish politician, 1873–1936) Oscar von Sydow
- Oscar Wilde
- Óscar Yanes — Venezuelan Journalist, Broadcaster and Author Oscar Yanes
- Oscar's Oasis
- Oscarino Costa Silva — early Brazilian footballer (1907–1990) Oscarino Costa Silva
- Osceola County, Florida: overview, geography, history and communities Osceola County, Florida
- Osceola County, Iowa
- Osceola County, Michigan
- Osceola, Arkansas
- Osceola, Iowa: county seat and community in Clarke County Osceola, Iowa
- Oschiri — town and comune in Sardinia, Italy Oschiri
- Oscillation
- Oscilloscope — Instrument for Displaying Electrical Signals Oscilloscope
- Oscilloscope Laboratories
- Osco — former municipality in Leventina, Ticino, Switzerland Osco
- Oscoda County, Michigan: Overview, Geography and Recreation Oscoda County, Michigan
- Oséas (Oséas Reis dos Santos) — Brazilian footballer Oséas
- Osenbach (Haut-Rhin) Osenbach
- Osgoode Hall Law School
- Oshana Region, Namibia: geography, economy, culture, and environment Oshana Region
- Oshawa, Ontario Oshawa
- Oshikoto Region (Namibia) Oshikoto Region
- Oshima Province (former Japanese province on Hokkaido) Oshima Province
- Oshkosh, Wisconsin
- OSI model: Seven-layer framework for network communication OSI model
- Osidda — small mountain comune in Sardinia, Italy Osidda
- Osijek — regional center of Slavonia in eastern Croatia Osijek
- Osijek-Baranja County — geography, history, economy and attractions Osijek-Baranja County
- Osilo — town and comune in the Province of Sassari, Sardinia, Italy Osilo
- Osini — small comune in Nuoro province, Sardinia Osini
- Osip Mandelstam: life, poetry, and legacy Osip Mandelstam
- Osiris: Egyptian god of the afterlife, resurrection, and fertility Osiris
- Oskaloosa, Iowa
- Oskaloosa, Kansas — county seat in northeastern Kansas Oskaloosa, Kansas
- Oskar Fischer (1923–2020) — East German politician and foreign minister Oskar Fischer
- Oskar Gröning: SS administrative staff at Auschwitz Oskar Gröning
- Oskar Heinroth — German biologist and pioneer of animal behaviour studies Oskar Heinroth
- Oskar Kokoschka: Austrian Expressionist Painter, Poet and Playwright Oskar Kokoschka
- Oskar Lafontaine
- Oskar Leimgruber — Swiss Federal Chancellor (1944–1951) Oskar Leimgruber
- Oskar Schindler
- Oskar Sundqvist — Swedish ice hockey centre and NHL player Oskar Sundqvist
- Oskarshamn — coastal town in Kalmar County, Sweden Oskarshamn
- Oskarshamn Municipality
- Oslo: Norway’s Capital — Geography, History, Culture, and Government Oslo
- Oslo Accords
- Oslofjord: geography, history, uses and notable features Oslofjord
- Osly-Courtil — commune in Aisne, northern France Osly-Courtil
- Osmaniye (city in southern Turkey) Osmaniye
- Osmanville (Calvados, Normandy) Osmanville
- Osmium (Os) — the densest naturally occurring element and a rare platinum-group metal Osmium
- Osmoregulation: how organisms control water and salt balance Osmoregulation
- Osmosis: solvent movement through semipermeable membranes Osmosis
- Osnabrück — city in Lower Saxony, Germany Osnabrück
- Osnabrück (district)
- Oso, Washington
- Osogna — former municipality in Ticino, Switzerland Osogna
- Osorno, Chile: City and Provincial Capital in the Los Lagos Region Osorno, Chile
- Osornophryne — Andean plump toads Osornophryne
- Osoyoos, British Columbia
- Osprey (Pandion haliaetus): the fish-eating raptor Osprey
- Osroene (Kingdom of Edessa) Osroene
- Ossas-Suhare — commune in the Pyrénées-Atlantiques of southwestern France Ossas-Suhare
- Osse-en-Aspe — a commune in the Aspe Valley of the Pyrénées-Atlantiques Osse-en-Aspe
- Ossenx — commune in Pyrénées-Atlantiques, southwestern France Ossenx
- Osserain-Rivareyte — commune in Pyrénées-Atlantiques, France Osserain-Rivareyte
- Ossès (commune in the French Basque Country) Ossès
- Ossi, a town and comune in Sardinia, Italy Ossi
- Ossian, Iowa
- Ossicles (malleus, incus, stapes) — the ear's tiny bones Ossicles
- Ossie Davis
- Ossingen: a municipality in Andelfingen district, Canton of Zurich Ossingen
- Ossipee, New Hampshire: town overview and regional profile Ossipee, New Hampshire
- Ostabat-Asme: commune in Pyrénées-Atlantiques and historic pilgrimage crossroads Ostabat-Asme
- Ostafrikasaurus: Late Jurassic theropod known from a single tooth Ostafrikasaurus
- Ostalbkreis — district in eastern Baden-Württemberg, Germany Ostalbkreis
- Ostallgäu (rural district in Swabia, Bavaria) Ostallgäu
- Ostara — Vernal equinox festival in modern Pagan and Wiccan practice Ostara
- Osteen, Florida: a concise guide to the unincorporated Volusia County community Osteen, Florida
- Osteichthyes — the bony fishes Osteichthyes
- Ostel (Aisne) — commune in northern France Ostel
- Osteoarthritis
- Osteogenesis imperfecta (brittle bone disease) Osteogenesis imperfecta
- Osteology: the scientific study of bones and the skeleton Osteology
- Osteopathy: principles, history, techniques, and clinical uses Osteopathy
- Osteoporosis — causes, symptoms, diagnosis, prevention and treatment Osteoporosis
- Österåker Municipality
- Österbymo — administrative centre of Ydre Municipality in Östergötland, Sweden Österbymo
- Osterdock, Iowa
- Östergötland
- Östergötland County: region, history, economy and culture Östergötland County
- Osterholz (district), Lower Saxony, Germany Osterholz
- Ostermundigen — municipality in the canton of Bern, Switzerland Ostermundigen
- Osterode (district)
- Östers IF
- Östersund — regional center of Jämtland in central Sweden Östersund
- Östersund Municipality — regional centre of Jämtland, Sweden Östersund Municipality
- Östersunds FK: Swedish football club from Östersund Östersunds FK
- Östhammar — coastal town and municipal seat in Uppsala County, Sweden Östhammar
- Östhammar Municipality: coastal municipality in Uppsala County, Sweden Östhammar Municipality
- Ostheim (Haut-Rhin) Ostheim, Haut-Rhin
- Ostholstein (district), Schleswig-Holstein, Germany Ostholstein
- Ostinato: repeated musical patterns and their uses Ostinato
- Ostprignitz-Ruppin (district) Ostprignitz-Ruppin
- Östra Göinge Municipality (Östra Göinge kommun) Östra Göinge Municipality
- Ostra, Suceava County, Romania Ostra, Suceava
- Ostracod (seed shrimp): biology, diversity, ecology, and fossil importance Ostracod
- Ostracoderms: Armoured Jawless Fishes of the Early Paleozoic Ostracoderm
- Ostrava: Industrial heritage and cultural hub in the Czech Republic Ostrava
- Ostreidae (true oysters): biology, uses, and distinctions Ostreidae
- Ostreoida: the bivalve order including oysters and scallops Ostreoida
- Ostreville, Pas-de-Calais — a commune in northern France Ostreville
- Ostrich (Struthio camelus) — large flightless bird of Africa Ostrich
- Ostrobothnia (region)
- Ostrogoths: Origins, Kingdoms, and Legacy Ostrogoths
- Ostroveni: commune in Dolj County, Romania Ostroveni
- Ostrów Mazowiecka: regional seat in Masovian Voivodeship, Poland Ostrów Mazowiecka
- Ostvorpommern — former district in Mecklenburg-Western Pomerania Ostvorpommern
- Ostwald process — industrial production of nitric acid Ostwald process
- Osu! Tatakae! Ouendan (Hey! Fight! Cheer Squad) Osu! Tatakae! Ouendan
- Ōsumi (satellite)
- Ōsumi Province (Ōsumi no Kuni) Ōsumi Province
- Osvaldo Ardiles — Argentine footballer and coach Osvaldo Ardiles