Search by letter: O
Search by letter
Search by letter: O
- Oran: Algerian Coastal City, Port, and Cultural Center Oran
- Oran Province (Wilaya of Oran) — Overview, geography, history and economy Oran Province
- Orange: fruit, color, and place names Orange
- Orange (color)
- Orange (fruit): overview, characteristics, history, uses and varieties Orange (fruit)
- Orange Beach, Alabama: Gulf Coast city and resort community Orange Beach, Alabama
- Orange Bowl (college football bowl game) Orange Bowl
- Orange Caramel (South Korean K-pop sub-unit) Orange Caramel
- Orange City, Florida
- Orange City, Iowa: Dutch heritage, tulips, and a college town Orange City, Iowa
- Orange County
- Orange County, California: overview, geography, history, economy and attractions Orange County, California
- Orange County, Florida
- Orange County, Indiana
- Orange County, New York: overview, geography, history and economy Orange County, New York
- Orange County, North Carolina
- Orange County, Texas
- Orange County, Vermont
- Orange County, Virginia
- Orange Cove, California
- Orange flower water (orange blossom water) Orange flower water
- Orange Free State (historic Boer republic) Orange Free State
- Orange Is the New Black
- Orange juice
- Orange Line (CTA)
- Orange Park, Florida
- Orange Range
- Orange River (Oranje / Senqu) Orange River
- Orange Studio — French film and television production arm of Orange S.A. Orange Studio
- Orange Walk District, Belize Orange Walk District
- Orange Walk Town, Belize — overview, history and economy Orange Walk Town
- Orange-breasted sunbird (Anthobaphes violacea) Orange-breasted sunbird
- Orange-red — the color between orange and red Orange-red
- Orange-thighed frog (Litoria xanthomera) Orange-thighed frog
- Orange, California
- Orange, New Jersey
- Orange, New South Wales
- Orange, Ohio: village history, setting, and notable facts Orange, Ohio
- Orange, Texas
- Orange, Vaucluse
- Orange, Virginia
- Orange, Wisconsin (town in Juneau County) Orange, Wisconsin
- Orangeburg County, South Carolina
- Orangeburg, South Carolina: The Garden City and County Seat Orangeburg, South Carolina
- Orangeman's Day (The Twelfth) Orangeman's Day
- Orangutan (genus Pongo) Orangutan
- Orani — town and comune in the Province of Nuoro, Sardinia Orani
- Oranienburg — town north of Berlin Oranienburg
- Oranienburg concentration camp (1933–1934) Oranienburg concentration camp
- Oranjestad, Aruba
- Orator: public speaking, rhetoric, history and influence Orator
- Oratorio: form, history, structure, and notable works Oratorio
- Orbe — Swiss town in Vaud with Roman remains, industry and cultural sites Orbe
- Orbe District (Vaud, Switzerland) Orbe (district)
- Orbec (Calvados) — commune in Normandy, northwestern France Orbec
- Orbetello: Lagoon town in southern Tuscany Orbetello
- Orbey — commune in Haut-Rhin, Grand Est, France Orbey
- Orbit (astronomy and mechanics) Orbit
- Orbital (relating to orbits, orbitals, and orbital regions) Orbital
- Orbital eccentricity
- Orbital forcing and Milankovitch cycles Orbital forcing
- Orbital inclination: definition, measurement, and significance Orbital inclination
- Orbital period
- Orbital Plane (Astronomy): Definition, Properties, and Significance Orbital plane (astronomy)
- Orbital resonance: dynamics, examples, and significance Orbital resonance
- Orbital revolution: motion of planets, moons and satellites Orbital revolution
- Orbital speed
- Orbiting Carbon Observatory (OCO) Orbiting Carbon Observatory
- Orc: Mythical Origins, Literary Development, and Modern Fantasy Orc
- Orchard: cultivation and uses of fruit- and nut-bearing trees Orchard
- Orchard City, Colorado
- Orchard Grass Hills, Kentucky
- Orchard Island, Ohio
- Orchard MRT station (NS22 / TE14) Orchard MRT station
- Orchard Road — Singapore's principal shopping and entertainment boulevard Orchard Road
- Orchard, Iowa — small city in the United States Orchard, Iowa
- Orchestra: structure, history, repertoire, and common distinctions Orchestra
- Orchestra pit: design, function, and notable examples Orchestra pit
- Orchestration (music): craft, instruments, history, and techniques Orchestration
- Orchestre de Paris
- Orchid (Orchidaceae): overview, biology, uses and conservation Orchid
- Orchid (color)
- ORCID (Open Researcher and Contributor ID) ORCID
- Ord, Nebraska
- Order (concept) Order
- Order (biology): taxonomic rank in classification Order (biology)
- Order of Australia
- Order of Canada
- Order of Jamaica
- Order of Lenin
- Order of Leopold (Belgium)
- Order of magnitude approximation of the logarithm of a value
- Order of Merit an award, for notable work in the armed forces, science, art, literature, or for the promotion of culture
- Order of Merit of the Italian Republic
- Order of operations (operator precedence and associativity) Order of operations
- Order of Prince Henry (Ordem do Infante Dom Henrique) Order of Prince Henry
- Order of Santiago
- Most Distinguished Order of St Michael and St George Order of St Michael and St George
- Order of succession (transfer of authority in monarchies, states and institutions) Order of succession
- Order of the Aztec Eagle: Mexico's Highest Honor for Foreign Nationals Order of the Aztec Eagle
- The Most Honourable Order of the Bath Order of the Bath
- Order of the British Empire
- Order of the Companions of Honour
- Order of the Federal Republic (Nigeria) Order of the Federal Republic
- Most Noble Order of the Garter Order of the Garter
- Most Eminent Order of the Indian Empire Order of the Indian Empire
- Order of the Phoenix (fictional secret society) Order of the Phoenix
- Order of the Rising Sun
- Order of the Solar Temple — origins, beliefs, events and legacy Order of the Solar Temple
- The Most Exalted Order of the Star of India Order of the Star of India
- Most Ancient and Most Noble Order of the Thistle Order of the Thistle
- Order of the White Eagle (Poland)
- Order theory: partial orders, lattices, and applications Order theory
- Ordered pair
- Orders of Magnitude of Time Orders of magnitude (time)
- Ordiarp — commune in Pyrénées-Atlantiques, southwestern France Ordiarp
- Ordinal number
- Ordinary differential equation (ODE) Ordinary differential equation
- Ordinary language philosophy: method, history, and influence Ordinary language philosophy
- Ordinary Least Squares (OLS): method, properties, and applications Ordinary least squares
- Ordinary Love (U2 song)
- Ordinary People (1980 film) Ordinary People
- Ordinary Seaman (naval rank) Ordinary seaman (rank)
- Ordino — parish and town in northern Andorra Ordino
- Ordnance Survey
- Ordnance Survey National Grid
- Ordo Templi Orientis (O.T.O.): history, organization, and practices Ordo Templi Orientis
- Ordonnac — commune in Gironde, southwestern France Ordonnac
- Ordonnaz
- Ordos (Inner Mongolia) — prefecture-level city in the Ordos Loop Ordos City
- Ordovician period Ordovician
- Ordu: Black Sea Coastal City and Provincial Center in Northern Turkey Ordu
- Ordubad District — Nakhchivan region of Azerbaijan Ordubad District
- Orduspor — Turkish football club from Ordu Orduspor
- Ore: naturally occurring mineral deposits containing extractable metals Ore
- Ore Mountains (Erzgebirge / Krušné hory): geography, mining and cultural heritage Ore Mountains
- Örebro — city in central Sweden Örebro
- Örebro County
- Örebro HK
- Örebro Municipality
- Örebro SK — Swedish football club from Örebro Örebro SK
- Oreco (Brazilian footballer, born 1922) Oreco
- Oregano (Origanum vulgare) Oregano
- Oregon: geography, history, culture, and economy of a Pacific Northwest state Oregon
- Oregon City — history, geography, and landmarks Oregon City, Oregon
- Concordia University (Portland, Oregon) Oregon Concordia University
- Oregon County, Missouri
- Oregon Inlet (Outer Banks, North Carolina) Oregon Inlet
- Oregon State University
- Oregon Territory (U.S. organized territory, 1848–1859) Oregon Territory
- Oregon Trail (19th-century overland migration route) Oregon Trail
- Oregon, Illinois
- Oregon, Missouri
- Oregon, Ohio
- Oregrounds iron — Swedish bar iron prized for steelmaking Oregrounds iron
- Öregrund — coastal town in Uppsala County, Sweden Öregrund
- Orègue (commune in Pyrénées-Atlantiques, France) Orègue
- Oreland, Pennsylvania
- Orellana Province
- Orem, Utah
- Oreo (cookie) Oreo
- Oreophrynella — bush toads of the Guiana Shield tepuis Oreophrynella
- Øresund Bridge: road and rail link between Denmark and Sweden Oresund Bridge
- Oreye — municipality in Liège province, Wallonia, Belgium Oreye
- ORF — Österreichischer Rundfunk, Austria's public broadcaster ORF (broadcaster)
- Orford, Suffolk: village, castle and coastal reserve Orford
- Organ (biology, musical instrument, and institutional uses) Organ
- Organ (biology) Organ (anatomy)
- Organ (musical instrument) Organ (music)
- Organ donation and transplantation Organ donation
- Organ system
- Organelle (cell biology): structure, types, and function Organelle
- Organic: Concepts in Chemistry, Biology, and Agriculture Organic
- Organic chemistry: principles, structures, reactions and applications Organic chemistry
- Organic compound
- Organic farms: practices, benefits, certification, and challenges Organic farms
- Organic light-emitting diode (OLED): principles, history, and applications Organic light-emitting diode
- Organic matter: definition, roles in soil, ecology and climate Organic matter
- Organic reactions: types, mechanisms, and applications Organic reaction
- Organic synthesis: principles, methods, history and applications Organic synthesis
- Organisation for the Prohibition of Chemical Weapons (OPCW) Organisation for the Prohibition of Chemical Weapons
- Organisation internationale de la Francophonie (OIF) Organisation internationale de la Francophonie
- Organisation of Islamic Cooperation: purpose, structure, and activities Organisation of Islamic Cooperation
- Commissioner for Philately and Scripophily (Soviet organization) Organisation of the Commissioner for Philately and Scripophily
- Organism: definition, features, organization, and borderline cases Organism
- Organization: concept, structures, history, functions and types Organization
- Organization for Security and Co-operation in Europe (OSCE) Organization for Security and Co-operation in Europe
- Organization of American States
- Organized crime: structure, activities, history, and social effects Organized crime
- Organolithium reagent
- Organometallic chemistry: metal–carbon compounds, reactions and applications Organometallic chemistry
- Organotroph: organisms that use organic molecules as electron donors Organotroph
- Orgasm (sexual climax) Orgasm
- Orges, a municipality in Jura-Nord Vaudois, Canton of Vaud, Switzerland Orges, Switzerland
- Orgeval (Aisne) — Commune in northern France Orgeval, Aisne
- Orgnac-l'Aven
- Orgon — commune in Bouches-du-Rhône, Provence, France Orgon
- Orgosolo: Sardinian town known for murals, landscape and pastoral traditions Orgosolo
- Örgryte IS — Swedish sports club and historic football team Örgryte IS
- Orgy: meanings, history and contemporary context Orgy
- Orgy (American alternative metal band) Orgy (band)
- Orhan Pamuk: Life, Major Works, Themes and Controversies Orhan Pamuk
- Oriana Fallaci
- Oribe Peralta
- Oriel College, Oxford
- Orient (term for the east) Orient
- Orient Express
- Orient, Illinois: overview of a small Midwestern community Orient, Illinois
- Orient, Iowa
- Orientability in topology and geometry Orientability
- Oriental Longhair
- Oriental magpie-robin (Copsychus saularis) Oriental magpie-robin
- Oriental Orthodoxy
- Oriental Pearl Tower
- Oriental studies: scope, history, and contemporary perspectives Oriental studies
- Oriental Telephone Company
- Oriental turtle dove (Streptopelia orientalis) — overview and natural history Oriental turtle dove
- Orientation
- Orienteering: map-and-compass navigation sport and outdoor activity Orienteering
- Origa (Olga Vitalyevna Yakovleva): Russian singer active in Japan Origa
- Origami: The Art and Practice of Paper Folding Origami
- Origanum: the genus of oregano and marjoram — overview, traits, and uses Origanum
- Origen: Early Christian Theologian, Exegete and Controversial Thinker Origen
- Origin of Birds: Evolutionary Transition from Theropod Dinosaurs Origin of birds
- Origin of life: hypotheses, evidence, and open questions Origin of life
- Origin of Symmetry (Muse album) Origin of Symmetry
- Original sin (Christian doctrine) Original sin
- Original Six (NHL) — the six teams of 1942–1967 Original Six
- Origins of the Blues: Roots, Development, and Musical Characteristics Origins of the blues
- Origlio (Ticino) — Swiss municipality and the nearby lake Origlio
- Origne — commune in Gironde, southwestern France Origne
- Origné, Mayenne: Commune in Pays de la Loire, France Origné
- Origny-en-Thiérache: commune in the Thiérache region of northern France Origny-en-Thiérache
- Origny-Sainte-Benoite
- Orihuela: historic city of the Vega Baja in Alicante, Spain Orihuela
- Orillia, Ontario Orillia
- Orimattila, Finland Orimattila
- Orin, Pyrénées-Atlantiques
- Orinoco River: Geography, Ecology and Human Uses Orinoco
- Oriole (Old World orioles, genus Oriolus) Oriole
- Oriole Park at Camden Yards
- Orion (constellation) Orion
- Orion (constellation): stars, nebulae, mythology and visibility Orion (constellation)
- Orion (mythology)
- Orion (spacecraft)
- Orion Arm (Local Spur) — the Solar System's region of the Milky Way Orion Arm
- Orion Molecular Cloud Complex Orion complex
- Orion Nebula (Messier 42) — nearest bright region of massive star formation Orion nebula
- Orion Pictures
- Orion, Pyrénées-Atlantiques (commune in southwestern France) Orion, Pyrénées-Atlantiques
- Orion's Belt
- Oristano
- Oritsé Williams: English singer, songwriter and founding member of JLS Oritsé Williams
- Orivesi — town and municipality in Pirkanmaa, Finland Orivesi
- Orix Buffaloes (Nippon Professional Baseball team) Orix Buffaloes
- Oriya (Odia) film industry — Ollywood Oriya film industry
- Odia Wikipedia (Oriya Wikipedia) Oriya Wikipedia
- Orizaba, Veracruz — city at the foot of Pico de Orizaba Orizaba
- Örkelljunga — locality in Skåne, Sweden Örkelljunga
- Örkelljunga Municipality
- Orkney Islands: an archipelago in the Northern Isles of Scotland Orkney Islands
- Orland Park, Illinois
- Orland, California — city in Glenn County Orland, California
- Orlande de Lassus: Renaissance master of polyphony Orlande de Lassus
- Orlando Bloom: English actor known for Legolas and blockbuster roles Orlando Bloom
- Orlando Brown (American actor, voice artist and musician) Orlando Brown
- Orlando Cepeda: Puerto Rican Hall of Fame First Baseman Orlando Cepeda
- Orlando City SC
- Orlando Cole (1908–2010) — American cello pedagogue Orlando Cole
- Orlando Gibbons (1583–1625) Orlando Gibbons
- Orlando International Airport (MCO) — Overview, History and Operations Orlando International Airport
- Orlando Jones — American comedian, actor, writer and producer Orlando Jones
- Orlando Jordan: Career and Biography of an American Professional Wrestler Orlando Jordan
- Orlando Letelier
- Orlando Magic (National Basketball Association franchise) Orlando Magic
- 2016 Orlando nightclub shooting (Pulse attack) Orlando nightclub shooting
- Orlando Peçanha de Carvalho
- Orlando Pride
- Orlando, Florida: Central Florida City Known for Tourism and Growth Orlando, Florida
- Orlando, Oklahoma — small town profile Orlando, Oklahoma
- Orléans, city on the Loire in north-central France Orléans
- Orleans (American soft rock band) Orleans (band)
- Orleans County, New York
- Orleans County, Vermont
- Orleans, Iowa
- Orlov diamond
- Orly — commune near Paris and namesake of Paris–Orly Airport Orly
- Orly Airport (Paris-Orly) Orly Airport
- Orly Levy-Abekasis: Israeli politician and founder of Gesher Orly Levy-Abekasis
- Ormalingen (Basel-Landschaft, Switzerland) Ormalingen
- Ormara: Port City on Pakistan’s Makran Coast Ormara
- Ormoc: city of Leyte, Philippines — geography, history, economy and notable facts Ormoc
- Ormond Beach, Florida — coastal city and historic resort community Ormond Beach, Florida
- Ormont-Dessous
- Ormont-Dessus: Alpine municipality and resort in canton Vaud Ormont-Dessus
- Ormoy (Yonne) Ormoy, Yonne
- Ormskirk, West Lancashire Ormskirk
- Orna Porat: German‑born Israeli stage actress and advocate for children's theatre Orna Porat
- Ornaisons — commune in Aude, Occitanie, France Ornaisons
- Ornamental plant: decorative horticulture, uses and cultivation Ornamental plant