All articles starting with O
9,097 articles
Osmania University (عثمانیہ یونیورسٹی)
Osmania University (عثمانیہ یونیورسٹی), a public state university in Hyderabad founded 1917–1918 by Nizam Osman Ali Khan, first in India to teach in Urdu; NAAC A+ and NIRF-ranked.
Osmaniye (city)
Osmaniye, city in southern Turkey, seat of Osmaniye Province on the Ceyhan River plain. Province population 564,123 (2025), 83.63% urban; first-degree earthquake zone on the East Anatolian Fault; 2023 quakes damaged thousands of buildings.
Osmanlı Müellifleri
Osmanlı Müellifleri is a three-volume bio-bibliographical dictionary of Ottoman authors compiled by the bibliographer Bursalı Mehmed Tâhir, published in Istanbul from 1915 to 1926.
Osmanoğlu family
The Osmanoğlu family is the modern descendant of the Ottoman dynasty, which ruled the empire for 625 years until its abolition in 1924, resulting in the exile of all 157 members.
Osmanthorpe Roman vexillation fortress
Osmanthorpe Roman vexillation fortress (Osmanthorpe Camp), Edingley, Nottinghamshire: a scheduled 1st-century double-ditched Roman military enclosure of 8.8 ha, known from cropmarks, one of 14 recorded in England.
Osmanthus
Osmanthus (sweet olive, tea olive; 桂花 for O. fragrans) is a genus of about 26–30 fragrant evergreen Oleaceae shrubs from Türkiye to Japan and Indo-China, used in tea, food, and perfumery.
Osmanthus fragrans
Osmanthus fragrans (桂花, guìhuā), sweet osmanthus or tea olive, is an Oleaceae tree native from the Himalaya to southern Japan, cultivated in China for 2,500 years for fragrant flowers used in tea, sweets, medicine, and perfumery.
Osmanthus Rain
Osmanthus Rain (桂花雨) is a prose essay by the Taiwanese writer Qi Jun, published in 1976, recalling shaking osmanthus blossoms in childhood Zhejiang and expressing her lifelong homesickness.
Osmerus eperlanus
Osmerus eperlanus, the European smelt (sparling), is a small anadromous osmerid fish from the White Sea to the Gironde estuary, with landlocked lake populations; spawns February to May, reaches 45 cm, IUCN least concern but ICES data deficient.
Osmerus mordax
Osmerus mordax, the rainbow smelt, is a small anadromous or landlocked Osmeridae fish of northeastern North America, introduced widely as forage, commercially harvested, with endangered Lake Utopia populations.
Osmeterium
Osmeterium (plural osmeteria): the forked, eversible defensive scent gland of swallowtail butterfly (Papilionidae) caterpillars, extruded from the prothorax when alarmed to smear predators with foul-smelling terpene repellents that vary by species.
Osmia cornifrons
Osmia cornifrons, the horn-faced or Japanese orchard bee (mame-ko bee), is a solitary mason bee native to Japan, managed for apple pollination there for over 80 years, introduced to the US in 1965 and 1977, and naturalized in eastern North America.
Osmium
Osmium is a hard, bluish-silver platinum-group metal, atomic number 76, often cited as the densest element, discovered in 1803 and known for its very toxic tetroxide and hard, wear-resistant alloys.
Osmium tetroxide
Osmium tetroxide (OsO4), also called osmic acid, is a volatile, highly poisonous oxide of osmium used as a fixative and stain in electron microscopy and as a reagent for cis-dihydroxylation of alkenes.
Osmometry
Osmometry is a family of analytical techniques that measure the osmotic pressure or osmolality of a solution, using vapor pressure, freezing point, or membrane methods to determine solute concentration and molecular weight.
Osmond Fisher
Osmond Fisher (1817–1914) was an English clergyman and geologist, rector of Harlton, who wrote the first geophysics textbook, The Physics of the Earth's Crust (1881), anticipating convection currents and continental mobility.
Osmoregulation
Osmoregulation is the active control of water and electrolyte balance in organisms. Marine animals are hyposmotic to seawater, freshwater animals hyperregulate, and mammals use osmoreceptors, kidneys, and hormones to defend osmotic set-points.
Osmosis
Osmosis, from the Greek for "push," is the net movement of water across a semipermeable membrane toward the higher solute concentration, quantified by van 't Hoff's law.
Osmosis (2019 TV series)
Osmosis is a 2019 French Netflix science-fiction series created by Audrey Fouché, 8 episodes set in near-future Paris, where a dating app implant matches soulmates by mining brain data; adapted from a 2015 Arte Creative web series by the Chiche brothers.
Osmosis Jones
Osmosis Jones (2001) is a Warner Bros. live-action/animated buddy cop comedy about a white blood cell fighting the virus Thrax inside Bill Murray's character; it flopped commercially but became a science-class staple.
Osmotherapy
Osmotherapy is the intravenous use of osmotic agents, principally mannitol and hypertonic saline, to draw water from brain tissue and lower intracranial pressure in cerebral edema.
Osmotic concentration
Osmotic concentration, also called osmotic strength or osmolarity, is the concentration of osmotically active particles in a solution, expressed as osmoles per liter or per kilogram.
Osmotic Fragility
Osmotic fragility (erythrocyte osmotic fragility test, OFT, NESTROFT, AGLT) measures red blood cell resistance to lysis in hypotonic saline; spherocytes in hereditary spherocytosis lyse at higher NaCl, thalassemia cells resist, and the test lacks specificity for autoimmune hemolytic anemia.
Osmotic physiology in hypersaline niches
Osmotic physiology in hypersaline niches is the study of how microorganisms balance water across cell membranes in brines too salty for most life, spanning the salt-in and salt-out strategies.
Osmotic pressure
Osmotic pressure, also known as osmotic potential, is the pressure needed to stop water flowing across a semipermeable membrane into a solution. It is a colligative property of solutions.
Osmund
Osmund, who died in 1099, was a Norman clerk who served William the Conqueror as chancellor and was Bishop of Salisbury from 1078, building Old Sarum cathedral.
Osmunda
Osmunda, royal ferns of Osmundaceae, a cosmopolitan genus of 13 wetland fern species published by Linnaeus in 1753, known as fossils since the Late Triassic about 220 million years ago.
Osmunda japonica
Osmunda japonica (zenmai, ゼンマイ; 紫萁; 고비), the Japanese royal fern, is an Osmundaceae fern from Pakistan to Sakhalin and Indochina with dimorphic 2-pinnate fronds, 2n=44, edible spring fiddleheads, and hybrids O. hybrida, O. × intermedia, O. × nipponica, and O. × mildei.
Osmunda regalis
Osmunda regalis, the royal fern, is an Old World Osmundaceae fern native from Europe and Macaronesia to Africa and Madagascar, hemidimorphic with apical fertile pinnae, IUCN least concern, and distinct from American O. spectabilis.
Osmundaceae
Osmundaceae (royal ferns), order Osmundales, a family of leptosporangiate ferns sister to all other leptosporangiates; fewer than 20 species in four to six genera but the richest fossil record of any extant fern group, from the Permian onward.