All articles starting with O
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Obukhov length
The Obukhov length, also called the Monin–Obukhov length, is a length scale characterizing stability of the atmospheric surface layer by comparing shear and buoyancy effects on turbulence.
Obverse and reverse
Obverse and reverse are the two faces of a coin: the obverse (heads) front, usually a monarch or issuer's insignia, and the reverse (tails) back. Assignment uses die-position rules for ancient coins and issuer-based conventions for modern ones, with the Euro as a noted exception.
Obvious Child
Obvious Child is a 2014 American romantic comedy directed by Gillian Robespierre, starring Jenny Slate as a Brooklyn comedian who decides to have an abortion.
ObZen
ObZen is the sixth studio album by Swedish extreme metal band Meshuggah, released in 2008, whose song "Bleed" became their signature track and a reference point for the djent style.
Óc Eo art
Óc Eo art is the art of the Funan kingdom's civilization in the Mekong Delta from the 1st to the 8th century CE, blending Indian influence with local craft.
OC Transpo
OC Transpo, formally the Ottawa-Carleton Regional Transit Commission since 1973, is the public transit agency of Ottawa, Ontario, operating buses, the O-Train light rail, and Para Transpo service.
OC&C Strategy Consultants
OC&C Strategy Consultants is a partner-owned pure strategy consultancy founded in London in 1987 by former Booz Allen Hamilton consultants, known for consumer goods, retail, and private equity advisory work.
Oca Ventures
OCA Ventures is an early-stage venture capital firm based in Chicago, Illinois, writing $1 million to $3 million checks in technology, healthcare, and scalable services companies.
OCA2
OCA2 (formerly P gene) is a chromosome 15 gene encoding a melanosomal transmembrane protein involved in melanin production and pH regulation; mutations cause oculocutaneous albinism type 2, and OCA2-HERC2 variants largely determine human eye color.
Ocado
Ocado (Ocado Group plc, LSE: OCDO) is a British technology and online grocery company founded in 2000. It runs Ocado Retail, a 50:50 M&S joint venture, and licenses its Ocado Smart Platform warehouse robotics to 15 grocery partners worldwide.
Ocala, Florida
Ocala, Florida: county seat and largest city of Marion County in north-central Florida, the "Horse Capital of the World" with about 600 thoroughbred farms, Silver Springs glass-bottom boats, and the fastest-growing U.S. metro in 2025.
Ocalenie
Ocalenie (Rescue) is a 1945 poetry collection by Czesław Miłosz, gathering poems written between 1932 and 1945, and ranked among the most important works of twentieth-century Polish poetry.
OCaml
OCaml, formerly Objective Caml, is a statically typed ML-family programming language created in 1996 at INRIA in France, combining functional, imperative, and object-oriented programming with automatic type inference.
Ocaña, Norte de Santander
Ocaña is a city and municipality in the Colombian department of Norte de Santander, founded in 1570 and known for hosting the Gran Convención of 1828.
Ocarina
Ocarina: a vessel flute, an enclosed-chamber wind instrument played through a windway with finger holes. Invented by Giuseppe Donati in Budrio, Italy, 1853; ancient American precedents from 1200 BCE; Helmholtz-resonator acoustics.
OCBC Bank
OCBC Bank, also known as Oversea-Chinese Banking Corporation, is a Singapore banking group formed in 1932 from a merger of three Hokkien banks, now Southeast Asia's second largest financial group.
OCC - The Options Clearing Corporation
The Options Clearing Corporation (OCC), founded in 1973 and headquartered in Chicago, is the world's largest equity derivatives clearer, clearing more than 12.2 billion options contracts in 2024.
Occam (programming language)
Occam is a concurrent programming language designed by David May at INMOS for the transputer, based on Hoare's CSP, in which processes communicate over synchronized one-way channels.
Occam's razor
Occam's razor, or Ockham's razor, is the principle of parsimony: prefer the explanation requiring fewer assumptions when evidence is otherwise equal. Named for William of Ockham, formalized in Bayesian model selection, and limited as a tie-breaker, not a truth guarantee.
Occaraba
Occaraba, an ancient town of Roman Syria on the Tabula Peutingeriana, also Orarabon, Ovvariba, Akoraba; identified with 'Agerbat/Uqayribat, Barrington Atlas 68 D3, Pleiades 668322, dated Roman/Late Antique.
Occasional poetry
Occasional poetry (German Gelegenheitsgedicht; related term Kasualpoesie) is verse written for a specific occasion, such as a wedding, baptism, or funeral, often on commission and for payment.
Occator (crater on Ceres)
Occator is a 92-km-wide, 4-km-deep impact crater on dwarf planet Ceres, centered at 19.82°N, 239.33°E, holding Ceres' brightest areas, Cerealia Facula and Vinalia Faculae: young sodium carbonate salt deposits from upwelling brines.
Occidental College
Occidental College (Oxy), founded 1887 in Boyle Heights and located in Eagle Rock, Los Angeles since 1914, is L.A.'s only liberal arts college, enrolling about 1,886 undergraduates; Barack Obama attended 1979-1981.
Occidental Mindoro
Occidental Mindoro, a Philippine province in MIMAROPA occupying western Mindoro Island, capital Mamburao, created 1950 by Republic Act No. 505; 11 municipalities, land area 5,879.85 sq km, population 511,417 (2024 census).
Occidental Petroleum
Occidental Petroleum Corporation, known as Oxy, is one of the largest United States oil and gas producers, founded in Los Angeles in 1920 and led for decades by Armand Hammer.
Occipital bone
Occipital bone (os occipitale): the unpaired skull bone forming the back and base of the cranium around the foramen magnum. Four parts (basilar, two condylar, squamous); articulates with parietals, temporals, sphenoid, atlas; dual endochondral and intramembranous ossification from week 8-9.
Occipital bun
Occipital bun (chignon): a posterior projection of the occipital squama characteristic of Neanderthals, present in 93.3% of sampled European Neandertals; a weaker 'hemibun' occurs in some modern humans and is likely not homologous.
Occipital horn syndrome
Occipital horn syndrome (OHS), formerly Ehlers-Danlos type IX or X-linked cutis laxa, is a rare X-linked recessive ATP7A copper-transport disorder with occipital exostoses, cutis laxa, bladder diverticula, and mild neurologic involvement, milder than Menkes disease.
Occipital lobe
Occipital lobe: smallest, rearmost cerebral lobe, housing the primary visual cortex (V1, calcarine sulcus) and dorsal/ventral visual streams; supplied by the posterior cerebral artery; damage causes homonymous field loss and cortical blindness.
Occipital nerve stimulation
Occipital nerve stimulation is a neuromodulation treatment in which leads implanted near the occipital nerves deliver electrical pulses to relieve refractory headache and facial pain, including occipital neuralgia and chronic migraine.