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21496 | https://en.wikipedia.org/wiki/Nucleic%20acid | Nucleic acid | Nucleic acids are large biomolecules that are crucial in all cells and viruses. They are composed of nucleotides, which are the monomer components: a 5-carbon sugar, a phosphate group and a nitrogenous base. The two main classes of nucleic acids are deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). If the sugar i... | Biology and health sciences | Biochemistry and molecular biology | null |
21497 | https://en.wikipedia.org/wiki/Nitrate | Nitrate | Nitrate is a polyatomic ion with the chemical formula . Salts containing this ion are called nitrates. Nitrates are common components of fertilizers and explosives. Almost all inorganic nitrates are soluble in water. An example of an insoluble nitrate is bismuth oxynitrate.
Chemical structure
The nitrate anion is th... | Physical sciences | Salts | null |
21505 | https://en.wikipedia.org/wiki/Nucleotide | Nucleotide | Nucleotides are organic molecules composed of a nitrogenous base, a pentose sugar and a phosphate. They serve as monomeric units of the nucleic acid polymers – deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), both of which are essential biomolecules within all life-forms on Earth. Nucleotides are obtained in th... | Biology and health sciences | Nucleic acids | Biology |
21506 | https://en.wikipedia.org/wiki/Numerical%20analysis | Numerical analysis | Numerical analysis is the study of algorithms that use numerical approximation (as opposed to symbolic manipulations) for the problems of mathematical analysis (as distinguished from discrete mathematics). It is the study of numerical methods that attempt to find approximate solutions of problems rather than the exact ... | Mathematics | Calculus and analysis | null |
21523 | https://en.wikipedia.org/wiki/Neural%20network%20%28machine%20learning%29 | Neural network (machine learning) | In machine learning, a neural network (also artificial neural network or neural net, abbreviated ANN or NN) is a model inspired by the structure and function of biological neural networks in animal brains.
An ANN consists of connected units or nodes called artificial neurons, which loosely model the neurons in the bra... | Technology | Artificial intelligence concepts | null |
21525 | https://en.wikipedia.org/wiki/Nutrition | Nutrition | Nutrition is the biochemical and physiological process by which an organism uses food to support its life. It provides organisms with nutrients, which can be metabolized to create energy and chemical structures. Failure to obtain the required amount of nutrients causes malnutrition. Nutritional science is the study of ... | Biology and health sciences | Health, fitness, and medicine | null |
21527 | https://en.wikipedia.org/wiki/Number%20theory | Number theory | Number theory is a branch of pure mathematics devoted primarily to the study of the integers and arithmetic functions. German mathematician Carl Friedrich Gauss (1777–1855) said, "Mathematics is the queen of the sciences—and number theory is the queen of mathematics." Number theorists study prime numbers as well as the... | Mathematics | Counting and numbers | null |
21530 | https://en.wikipedia.org/wiki/Nitroglycerin | Nitroglycerin | Nitroglycerin (NG) (alternative spelling of nitroglycerine), also known as trinitroglycerol (TNG), nitro, glyceryl trinitrate (GTN), or 1,2,3-trinitroxypropane, is a dense, colorless or pale yellow, oily, explosive liquid most commonly produced by nitrating glycerol with white fuming nitric acid under conditions approp... | Physical sciences | Esters and ethers | Chemistry |
21544 | https://en.wikipedia.org/wiki/Nuclear%20fusion | Nuclear fusion | Nuclear fusion is a reaction in which two or more atomic nuclei (for example, nuclei of hydrogen isotopes deuterium and tritium), combine to form one or more atomic nuclei and neutrons. The difference in mass between the reactants and products is manifested as either the release or absorption of energy. This difference... | Physical sciences | Nuclear physics | null |
21562 | https://en.wikipedia.org/wiki/NP%20%28complexity%29 | NP (complexity) | In computational complexity theory, NP (nondeterministic polynomial time) is a complexity class used to classify decision problems. NP is the set of decision problems for which the problem instances, where the answer is "yes", have proofs verifiable in polynomial time by a deterministic Turing machine, or alternativel... | Mathematics | Complexity theory | null |
21626 | https://en.wikipedia.org/wiki/Near-Earth%20object | Near-Earth object | A near-Earth object (NEO) is any small Solar System body orbiting the Sun whose closest approach to the Sun (perihelion) is less than 1.3 times the Earth–Sun distance (astronomical unit, AU). This definition applies to the object's orbit around the Sun, rather than its current position, thus an object with such an orbi... | Physical sciences | Solar System | Astronomy |
21652 | https://en.wikipedia.org/wiki/Natural%20language%20processing | Natural language processing | Natural language processing (NLP) is a subfield of computer science and especially artificial intelligence. It is primarily concerned with providing computers with the ability to process data encoded in natural language and is thus closely related to information retrieval, knowledge representation and computational lin... | Technology | Artificial intelligence concepts | null |
21655 | https://en.wikipedia.org/wiki/Nitric%20acid | Nitric acid | Nitric acid is an inorganic compound with the formula . It is a highly corrosive mineral acid. The compound is colorless, but samples tend to acquire a yellow cast over time due to decomposition into oxides of nitrogen. Most commercially available nitric acid has a concentration of 68% in water. When the solution conta... | Physical sciences | Inorganic compounds | null |
21664 | https://en.wikipedia.org/wiki/Nebula | Nebula | A nebula (; : nebulae, or nebulas) is a distinct luminescent part of interstellar medium, which can consist of ionized, neutral, or molecular hydrogen and also cosmic dust. Nebulae are often star-forming regions, such as in the Pillars of Creation in the Eagle Nebula. In these regions, the formations of gas, dust, and ... | Physical sciences | Basics_3 | null |
21675 | https://en.wikipedia.org/wiki/Natural%20resource | Natural resource | Natural resources are resources that are drawn from nature and used with few modifications. This includes the sources of valued characteristics such as commercial and industrial use, aesthetic value, scientific interest, and cultural value. On Earth, it includes sunlight, atmosphere, water, land, all minerals along wit... | Physical sciences | Basics_5 | null |
21689 | https://en.wikipedia.org/wiki/NTSC | NTSC | NTSC (from National Television System Committee) is the first American standard for analog television, published and adopted in 1941. In 1961, it was assigned the designation System M. It is also known as EIA standard 170.
In 1953, a second NTSC standard was adopted, which allowed for color television broadcast compat... | Technology | Broadcasting | null |
21690 | https://en.wikipedia.org/wiki/Number | Number | A number is a mathematical object used to count, measure, and label. The most basic examples are the natural numbers 1, 2, 3, 4, and so forth. Numbers can be represented in language with number words. More universally, individual numbers can be represented by symbols, called numerals; for example, "5" is a numeral that... | Mathematics | Mathematics | null |
21710 | https://en.wikipedia.org/wiki/Nerve%20agent | Nerve agent | Nerve agents, sometimes also called nerve gases, are a class of organic chemicals that disrupt the mechanisms by which nerves transfer messages to organs. The disruption is caused by the blocking of acetylcholinesterase (AChE), an enzyme that catalyzes the breakdown of acetylcholine, a neurotransmitter. Nerve agents ar... | Technology | Weapon of mass destruction | null |
21723 | https://en.wikipedia.org/wiki/Nonlinear%20optics | Nonlinear optics | Nonlinear optics (NLO) is the branch of optics that describes the behaviour of light in nonlinear media, that is, media in which the polarization density P responds non-linearly to the electric field E of the light. The non-linearity is typically observed only at very high light intensities (when the electric field of ... | Physical sciences | Optics | Physics |
21784 | https://en.wikipedia.org/wiki/Nova | Nova | A nova ( novae or novas) is a transient astronomical event that causes the sudden appearance of a bright, apparently "new" star (hence the name "nova", Latin for "new") that slowly fades over weeks or months. All observed novae involve white dwarfs in close binary systems, but causes of the dramatic appearance of a nov... | Physical sciences | Stellar astronomy | null |
21785 | https://en.wikipedia.org/wiki/Nuclear%20weapon | Nuclear weapon | A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission (fission or atomic bomb) or a combination of fission and fusion reactions (thermonuclear bomb), producing a nuclear explosion. Both bomb types release large quantities of energy from relatively small amount... | Technology | Weapons of mass destruction | null |
21830 | https://en.wikipedia.org/wiki/Nature | Nature | Nature is an inherent character or constitution, particularly of the ecosphere or the universe as a whole. In this general sense nature refers to the laws, elements and phenomena of the physical world, including life. Although humans are part of nature, human activity or humans as a whole are often described as at time... | Physical sciences | Science: General | null |
21833 | https://en.wikipedia.org/wiki/New%20moon | New moon | In astronomy, the new moon is the first lunar phase, when the Moon and Sun have the same ecliptic longitude. At this phase, the lunar disk is not visible to the naked eye, except when it is silhouetted against the Sun during a solar eclipse.
The original meaning of the term 'new moon', which is still sometimes used in... | Physical sciences | Celestial mechanics | Astronomy |
21837 | https://en.wikipedia.org/wiki/Nanometre | Nanometre | The nanometre (international spelling as used by the International Bureau of Weights and Measures; SI symbol: nm), or nanometer (American spelling), is a unit of length in the International System of Units (SI), equal to one billionth (short scale) or one thousand million (long scale) of a meter (0.000000001 m) and to ... | Physical sciences | Metric | Basics and measurement |
21848 | https://en.wikipedia.org/wiki/Neurosurgery | Neurosurgery | Neurosurgery or neurological surgery, known in common parlance as brain surgery, is the medical specialty that focuses on the surgical treatment or rehabilitation of disorders which affect any portion of the nervous system including the brain, spinal cord, peripheral nervous system, and cerebrovascular system. Neurosur... | Biology and health sciences | Surgery | Health |
21854 | https://en.wikipedia.org/wiki/Navigation | Navigation | Navigation is a field of study that focuses on the process of monitoring and controlling the movement of a craft or vehicle from one place to another. The field of navigation includes four general categories: land navigation, marine navigation, aeronautic navigation, and space navigation.
It is also the term of art us... | Technology | Navigation and timekeeping | null |
21865 | https://en.wikipedia.org/wiki/Neurotransmitter | Neurotransmitter | A neurotransmitter is a signaling molecule secreted by a neuron to affect another cell across a synapse. The cell receiving the signal, or target cell, may be another neuron, but could also be a gland or muscle cell.
Neurotransmitters are released from synaptic vesicles into the synaptic cleft where they are able to i... | Biology and health sciences | Neurotransmitters | Biology |
21869 | https://en.wikipedia.org/wiki/Neutron%20star | Neutron star | A neutron star is the collapsed core of a massive supergiant star. It results from the supernova explosion of a massive star—combined with gravitational collapse—that compresses the core past white dwarf star density to that of atomic nuclei. Surpassed only by black holes, neutron stars are the second smallest and dens... | Physical sciences | Stellar astronomy | null |
21918 | https://en.wikipedia.org/wiki/Normal%20subgroup | Normal subgroup | In abstract algebra, a normal subgroup (also known as an invariant subgroup or self-conjugate subgroup) is a subgroup that is invariant under conjugation by members of the group of which it is a part. In other words, a subgroup of the group is normal in if and only if for all and . The usual notation for this rela... | Mathematics | Abstract algebra | null |
21920 | https://en.wikipedia.org/wiki/Napalm | Napalm | Napalm is an incendiary mixture of a gelling agent and a volatile petrochemical (usually gasoline or diesel fuel). The name is a portmanteau of two of the constituents of the original thickening and gelling agents: coprecipitated aluminium salts of naphthenic acid and palmitic acid. A team led by chemist Louis Fieser o... | Technology | Incendiary weapons | null |
21935 | https://en.wikipedia.org/wiki/Nondeterministic%20Turing%20machine | Nondeterministic Turing machine | In theoretical computer science, a nondeterministic Turing machine (NTM) is a theoretical model of computation whose governing rules specify more than one possible action when in some given situations. That is, an NTM's next state is not completely determined by its action and the current symbol it sees, unlike a deter... | Mathematics | Theoretical computer science | null |
21938 | https://en.wikipedia.org/wiki/Neoproterozoic | Neoproterozoic | The Neoproterozoic Era is the last of the three geologic eras of the Proterozoic eon, spanning from 1 billion to 538.8 million years ago, and is the last era of the Precambrian "supereon". It is preceded by the Mesoproterozoic era and succeeded by the Paleozoic era of the Phanerozoic eon, and is further subdivided into... | Physical sciences | Geological timescale | Earth science |
21944 | https://en.wikipedia.org/wiki/Nervous%20system | Nervous system | In biology, the nervous system is the highly complex part of an animal that coordinates its actions and sensory information by transmitting signals to and from different parts of its body. The nervous system detects environmental changes that impact the body, then works in tandem with the endocrine system to respond to... | Biology and health sciences | Biology | null |
21958 | https://en.wikipedia.org/wiki/Nucleolus | Nucleolus | The nucleolus (; : nucleoli ) is the largest structure in the nucleus of eukaryotic cells. It is best known as the site of ribosome biogenesis. The nucleolus also participates in the formation of signal recognition particles and plays a role in the cell's response to stress. Nucleoli are made of proteins, DNA and RNA, ... | Biology and health sciences | Organelles | Biology |
21961 | https://en.wikipedia.org/wiki/Nucleon | Nucleon | In physics and chemistry, a nucleon is either a proton or a neutron, considered in its role as a component of an atomic nucleus. The number of nucleons in a nucleus defines the atom's mass number (nucleon number).
Until the 1960s, nucleons were thought to be elementary particles, not made up of smaller parts. Now they... | Physical sciences | Nuclear physics | Physics |
21989 | https://en.wikipedia.org/wiki/Nitrogen%20fixation | Nitrogen fixation | Nitrogen fixation is a chemical process by which molecular dinitrogen () is converted into ammonia (). It occurs both biologically and abiologically in chemical industries. Biological nitrogen fixation or diazotrophy is catalyzed by enzymes called nitrogenases. These enzyme complexes are encoded by the Nif genes (or ... | Technology | Soil and soil management | null |
22028 | https://en.wikipedia.org/wiki/Nephrology | Nephrology | Nephrology () is a specialty for both adult internal medicine and pediatric medicine that concerns the study of the kidneys, specifically normal kidney function (renal physiology) and kidney disease (renal pathophysiology), the preservation of kidney health, and the treatment of kidney disease, from diet and medication... | Biology and health sciences | Fields of medicine | Health |
22054 | https://en.wikipedia.org/wiki/Nuclear%20fission | Nuclear fission | Nuclear fission is a reaction in which the nucleus of an atom splits into two or more smaller nuclei. The fission process often produces gamma photons, and releases a very large amount of energy even by the energetic standards of radioactive decay.
Nuclear fission was discovered by chemists Otto Hahn and Fritz Strassm... | Physical sciences | Nuclear physics | null |
22071 | https://en.wikipedia.org/wiki/Nonsteroidal%20anti-inflammatory%20drug | Nonsteroidal anti-inflammatory drug | Non-steroidal anti-inflammatory drugs (NSAID) are members of a therapeutic drug class which reduces pain, decreases inflammation, decreases fever, and prevents blood clots. Side effects depend on the specific drug, its dose and duration of use, but largely include an increased risk of gastrointestinal ulcers and bleeds... | Biology and health sciences | Pain treatments | Health |
22102 | https://en.wikipedia.org/wiki/Naval%20mine | Naval mine | A naval mine is a self-contained explosive weapon placed in water to damage or destroy surface ships or submarines. Similar to anti-personnel and other land mines, and unlike purpose launched naval depth charges, they are deposited and left to wait until, depending on their fuzing, they are triggered by the approach of... | Technology | Naval warfare | null |
22131 | https://en.wikipedia.org/wiki/Natural%20gas | Natural gas | Natural gas (also called fossil gas, methane gas, or simply gas) is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane (95%) in addition to various smaller amounts of other higher alkanes. Traces of carbon dioxide, nitrogen, hydrogen sulfide, and helium are also usually present. Metha... | Technology | Energy | null |
22145 | https://en.wikipedia.org/wiki/Newton%27s%20method | Newton's method | In numerical analysis, the Newton–Raphson method, also known simply as Newton's method, named after Isaac Newton and Joseph Raphson, is a root-finding algorithm which produces successively better approximations to the roots (or zeroes) of a real-valued function. The most basic version starts with a real-valued function... | Mathematics | Real analysis | null |
22151 | https://en.wikipedia.org/wiki/Nuclear%20reactor | Nuclear reactor | A nuclear reactor is a device used to initiate and control a fission nuclear chain reaction. They are used for commercial electricity, marine propulsion, weapons production and research. When a fissile nucleus, usually uranium-235 or plutonium-239, absorbs a neutron, it splits into lighter nuclei, releasing energy, gam... | Technology | Power generation | null |
22153 | https://en.wikipedia.org/wiki/Nuclear%20power | Nuclear power | Nuclear power is the use of nuclear reactions to produce electricity. Nuclear power can be obtained from nuclear fission, nuclear decay and nuclear fusion reactions. Presently, the vast majority of electricity from nuclear power is produced by nuclear fission of uranium and plutonium in nuclear power plants. Nuclear de... | Technology | Energy | null |
22158 | https://en.wikipedia.org/wiki/Nuclear%20proliferation | Nuclear proliferation | Nuclear proliferation is the spread of nuclear weapons, fissionable material, and weapons-applicable nuclear technology and information to nations not recognized as "Nuclear Weapon States" by the Treaty on the Non-Proliferation of Nuclear Weapons, commonly known as the Non-Proliferation Treaty or NPT. Proliferation has... | Technology | Weapon of mass destruction | null |
22194 | https://en.wikipedia.org/wiki/Operating%20system | Operating system | An operating system (OS) is system software that manages computer hardware and software resources, and provides common services for computer programs.
Time-sharing operating systems schedule tasks for efficient use of the system and may also include accounting software for cost allocation of processor time, mass stora... | Technology | Operating systems | null |
22203 | https://en.wikipedia.org/wiki/Organic%20compound | Organic compound | Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-containing compounds such as alkanes (e.g. methane ) and its derivatives are univer... | Physical sciences | Chemical compounds: General | null |
22205 | https://en.wikipedia.org/wiki/Oasis | Oasis | In ecology, an oasis (; : oases ) is a fertile area of a desert or semi-desert environment that sustains plant life and provides habitat for animals. Surface water may be present, or water may only be accessible from wells or underground channels created by humans. In geography, an oasis may be a current or past rest s... | Physical sciences | Fluvial landforms | null |
22208 | https://en.wikipedia.org/wiki/Organic%20chemistry | Organic chemistry | Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, and reactions of organic compounds and organic materials, i.e., matter in its various forms that contain carbon atoms. Study of structure determines their structural formula. Study of properties includes p... | Physical sciences | Chemistry | null |
22210 | https://en.wikipedia.org/wiki/One-time%20pad | One-time pad | In cryptography, the one-time pad (OTP) is an encryption technique that cannot be cracked, but requires the use of a single-use pre-shared key that is larger than or equal to the size of the message being sent. In this technique, a plaintext is paired with a random secret key (also referred to as a one-time pad). Then,... | Technology | Computer security | null |
22213 | https://en.wikipedia.org/wiki/Operator%20%28mathematics%29 | Operator (mathematics) | In mathematics, an operator is generally a mapping or function that acts on elements of a space to produce elements of another space (possibly and sometimes required to be the same space). There is no general definition of an operator, but the term is often used in place of function when the domain is a set of function... | Mathematics | Mathematical analysis | null |
22265 | https://en.wikipedia.org/wiki/Ordovician | Ordovician | The Ordovician ( ) is a geologic period and system, the second of six periods of the Paleozoic Era, and the second of twelve periods of the Phanerozoic Eon. The Ordovician spans 41.6 million years from the end of the Cambrian Period Ma (million years ago) to the start of the Silurian Period Ma.
The Ordovician, named... | Physical sciences | Geological timescale | Earth science |
22266 | https://en.wikipedia.org/wiki/Oregano | Oregano | Oregano (, ; Origanum vulgare) is a species of flowering plant in the mint family, Lamiaceae. It was native to the Mediterranean region, but widely naturalised elsewhere in the temperate Northern Hemisphere.
Oregano is a woody perennial plant, growing to tall, with opposite leaves long. The flowers which can be whit... | Biology and health sciences | Herbs and spices | Plants |
22286 | https://en.wikipedia.org/wiki/Oligocene | Oligocene | The Oligocene ( ) is a geologic epoch of the Paleogene Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but the exact dates of the start and end of the epoch are slightly uncertain. Th... | Physical sciences | Geological timescale | Earth science |
22303 | https://en.wikipedia.org/wiki/Oxygen | Oxygen | Oxygen is a chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and a potent oxidizing agent that readily forms oxides with most elements as well as with other compounds. Oxygen is the most abundant element in Earth's crust, an... | Physical sciences | Chemistry | null |
22304 | https://en.wikipedia.org/wiki/Osmium | Osmium | Osmium () is a chemical element; it has symbol Os and atomic number 76. It is a hard, brittle, bluish-white transition metal in the platinum group that is found as a trace element in alloys, mostly in platinum ores. Osmium is the densest naturally occurring element. When experimentally measured using X-ray crystallogra... | Physical sciences | Chemical elements_2 | null |
22305 | https://en.wikipedia.org/wiki/Oxide | Oxide | An oxide () is a chemical compound containing at least one oxygen atom and one other element in its chemical formula. "Oxide" itself is the dianion (anion bearing a net charge of –2) of oxygen, an O2– ion with oxygen in the oxidation state of −2. Most of the Earth's crust consists of oxides. Even materials considered p... | Physical sciences | Inorganic compounds | null |
22332 | https://en.wikipedia.org/wiki/October | October | October is the tenth month of the year in the Julian and Gregorian calendars. Its length is 31 days. The eighth month in the old calendar of Romulus , October retained its name (from Latin and Greek ôctō meaning "eight") after January and February were inserted into the calendar that had originally been created by the ... | Technology | Months | null |
22350 | https://en.wikipedia.org/wiki/Osteichthyes | Osteichthyes | Osteichthyes ( ; ), also known as osteichthyans or commonly referred to as the bony fish, is a diverse superclass of vertebrate animals that have endoskeletons primarily composed of bone tissue. They can be contrasted with the Chondrichthyes (cartilaginous fish) and the extinct placoderms and acanthodians, which have e... | Biology and health sciences | Fishes | null |
22353 | https://en.wikipedia.org/wiki/Orrorin | Orrorin | Orrorin is an extinct genus of primate within Homininae from the Miocene Lukeino Formation and Pliocene Mabaget Formation, both of Kenya.
The type species is O. tugenenesis, named in 2001, and a second species, O. praegens, assigned to the genus in 2022.
Discovery and naming
Ororrin tugenensis
The first part of th... | Biology and health sciences | Australopithecines | Biology |
22362 | https://en.wikipedia.org/wiki/Ordered%20pair | Ordered pair | In mathematics, an ordered pair, denoted (a, b), is a pair of objects in which their order is significant. The ordered pair (a, b) is different from the ordered pair (b, a), unless a = b. In contrast, the unordered pair, denoted {a, b}, always equals the unordered pair {b, a}.
Ordered pairs are also called 2-tuples, ... | Mathematics | Set theory | null |
22373 | https://en.wikipedia.org/wiki/Object%20code | Object code | In computing, object code or object module is the product of an assembler or compiler.
In a general sense, object code is a sequence of statements or instructions in a computer language, usually a machine code language (i.e., binary) or an intermediate language such as register transfer language (RTL). The term indica... | Technology | Software development: General | null |
22385 | https://en.wikipedia.org/wiki/Oort%20cloud | Oort cloud | The Oort cloud (), sometimes called the Öpik–Oort cloud, is theorized to be a vast cloud of icy planetesimals surrounding the Sun at distances ranging from 2,000 to 200,000 AU (0.03 to 3.2 light-years). The concept of such a cloud was proposed in 1950 by the Dutch astronomer Jan Oort, in whose honor the idea was named.... | Physical sciences | Solar System | null |
22393 | https://en.wikipedia.org/wiki/Organelle | Organelle | In cell biology, an organelle is a specialized subunit, usually within a cell, that has a specific function. The name organelle comes from the idea that these structures are parts of cells, as organs are to the body, hence organelle, the suffix -elle being a diminutive. Organelles are either separately enclosed within ... | Biology and health sciences | Organelles and other cell parts | null |
22431 | https://en.wikipedia.org/wiki/Oracle%20machine | Oracle machine | In complexity theory and computability theory, an oracle machine is an abstract machine used to study decision problems. It can be visualized as a Turing machine with a black box, called an oracle, which is able to solve certain problems in a single operation. The problem can be of any complexity class. Even undecidabl... | Mathematics | Computability theory | null |
22433 | https://en.wikipedia.org/wiki/Orangutan | Orangutan | Orangutans are great apes native to the rainforests of Indonesia and Malaysia. They are now found only in parts of Borneo and Sumatra, but during the Pleistocene they ranged throughout Southeast Asia and South China. Classified in the genus Pongo, orangutans were originally considered to be one species. From 1996, they... | Biology and health sciences | Primates | null |
22444 | https://en.wikipedia.org/wiki/Orbital%20resonance | Orbital resonance | In celestial mechanics, orbital resonance occurs when orbiting bodies exert regular, periodic gravitational influence on each other, usually because their orbital periods are related by a ratio of small integers. Most commonly, this relationship is found between a pair of objects (binary resonance). The physical princi... | Physical sciences | Orbital mechanics | Astronomy |
22458 | https://en.wikipedia.org/wiki/Octahedron | Octahedron | In geometry, an octahedron (: octahedra or octahedrons) is a polyhedron with eight faces. One special case is the regular octahedron, a Platonic solid composed of eight equilateral triangles, four of which meet at each vertex. Regular octahedra occur in nature as crystal structures. Many types of irregular octahedra al... | Mathematics | Three-dimensional space | null |
22461 | https://en.wikipedia.org/wiki/Osteoporosis | Osteoporosis | Osteoporosis is a systemic skeletal disorder characterized by low bone mass, micro-architectural deterioration of bone tissue leading to more porous bone, and consequent increase in fracture risk.
It is the most common reason for a broken bone among the elderly. Bones that commonly break include the vertebrae in the s... | Biology and health sciences | Specific diseases | Health |
22469 | https://en.wikipedia.org/wiki/Ontogeny | Ontogeny | Ontogeny (also ontogenesis) is the origination and development of an organism (both physical and psychological, e.g., moral development), usually from the time of fertilization of the egg to adult. The term can also be used to refer to the study of the entirety of an organism's lifespan.
Ontogeny is the developmental ... | Biology and health sciences | Animal ontogeny | null |
22472 | https://en.wikipedia.org/wiki/Ophiuchus | Ophiuchus | Ophiuchus () is a large constellation straddling the celestial equator. Its name comes from the Ancient Greek (), meaning "serpent-bearer", and it is commonly represented as a man grasping a snake. The serpent is represented by the constellation Serpens. Ophiuchus was one of the 48 constellations listed by the 2nd-cen... | Physical sciences | Other | Astronomy |
22475 | https://en.wikipedia.org/wiki/Octans | Octans | Octans is a faint constellation located in the deep Southern Sky. Its name is Latin for the eighth part of a circle, but it is named after the octant, a navigational instrument. Devised by French astronomer Nicolas Louis de Lacaille in 1752, Octans remains one of the 88 modern constellations. The southern celestial pol... | Physical sciences | Other | Astronomy |
22479 | https://en.wikipedia.org/wiki/Olive | Olive | The olive, botanical name Olea europaea, meaning 'European olive', is a species of small tree or shrub in the family Oleaceae, found traditionally in the Mediterranean Basin, with wild subspecies found further afield in Africa and western Asia. When in shrub form, it is known as Olea europaea Montra, dwarf olive, or li... | Biology and health sciences | Lamiales | null |
22483 | https://en.wikipedia.org/wiki/Optics | Optics | Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultraviolet, and infrared light. Light is a type of electromagnetic radiation, and othe... | Physical sciences | Physics | null |
22497 | https://en.wikipedia.org/wiki/OpenGL | OpenGL | OpenGL (Open Graphics Library) is a cross-language, cross-platform application programming interface (API) for rendering 2D and 3D vector graphics. The API is typically used to interact with a graphics processing unit (GPU), to achieve hardware-accelerated rendering.
Silicon Graphics, Inc. (SGI) began developing OpenG... | Technology | Software development: General | null |
22498 | https://en.wikipedia.org/wiki/Orbit | Orbit | In celestial mechanics, an orbit (also known as orbital revolution) is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as a planet, moon, asteroid, or Lagrange point. ... | Physical sciences | Astronomy | null |
22513 | https://en.wikipedia.org/wiki/Ogg | Ogg | Ogg is a free, open container format maintained by the Xiph.Org Foundation. The authors of the Ogg format state that it is unrestricted by software patents and is designed to provide for efficient streaming and manipulation of high-quality digital multimedia. Its name is derived from "ogging", jargon from the computer ... | Technology | File formats | null |
22522 | https://en.wikipedia.org/wiki/Oscillation | Oscillation | Oscillation is the repetitive or periodic variation, typically in time, of some measure about a central value (often a point of equilibrium) or between two or more different states. Familiar examples of oscillation include a swinging pendulum and alternating current. Oscillations can be used in physics to approximate c... | Physical sciences | Basics_10 | null |
22526 | https://en.wikipedia.org/wiki/Organometallic%20chemistry | Organometallic chemistry | Organometallic chemistry is the study of organometallic compounds, chemical compounds containing at least one chemical bond between a carbon atom of an organic molecule and a metal, including alkali, alkaline earth, and transition metals, and sometimes broadened to include metalloids like boron, silicon, and selenium, ... | Physical sciences | Chemistry: General | null |
22544 | https://en.wikipedia.org/wiki/Common%20ostrich | Common ostrich | The common ostrich (Struthio camelus), or simply ostrich, is a species of flightless bird native to certain areas of Africa. It is one of two extant species of ostriches, the only living members of the genus Struthio in the ratite order of birds. The other is the Somali ostrich (Struthio molybdophanes), which has been ... | Biology and health sciences | Ratites | null |
22573 | https://en.wikipedia.org/wiki/Otorhinolaryngology | Otorhinolaryngology | Otorhinolaryngology ( , abbreviated ORL and also known as otolaryngology, otolaryngology–head and neck surgery (ORL–H&N or OHNS), or ear, nose, and throat (ENT)) is a surgical subspecialty within medicine that deals with the surgical and medical management of conditions of the head and neck. Doctors who specialize in t... | Biology and health sciences | Fields of medicine | null |
22581 | https://en.wikipedia.org/wiki/Estrogen | Estrogen | Estrogen (also spelled oestrogen in British English; see spelling differences) is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three major endogenous estrogens that have estrogenic hormonal activity: estrone (E1),... | Biology and health sciences | Biochemistry and molecular biology | null |
22594 | https://en.wikipedia.org/wiki/Omega-3%20fatty%20acid | Omega-3 fatty acid | Omega−3 fatty acids, also called omega−3 oils, ω−3 fatty acids or n−3 fatty acids, are polyunsaturated fatty acids (PUFAs) characterized by the presence of a double bond three atoms away from the terminal methyl group in their chemical structure. They are widely distributed in nature, are important constituents of anim... | Biology and health sciences | Lipids | Biology |
22595 | https://en.wikipedia.org/wiki/Ore | Ore | Ore is natural rock or sediment that contains one or more valuable minerals, typically including metals, concentrated above background levels, and that is economically viable to mine and process. The grade of ore refers to the concentration of the desired material it contains. The value of the metals or minerals a rock... | Physical sciences | Petrology | null |
22649 | https://en.wikipedia.org/wiki/Observation | Observation | Observation in the natural sciences is an act or instance of noticing or perceiving and the acquisition of information from a primary source. In living beings, observation employs the senses. In science, observation can also involve the perception and recording of data via the use of scientific instruments. The term m... | Physical sciences | Basics | null |
22654 | https://en.wikipedia.org/wiki/Ohio-class%20submarine | Ohio-class submarine | The Ohio class of nuclear-powered submarines includes the United States Navy's 14 ballistic missile submarines (SSBNs) and its four cruise missile submarines (SSGNs). Each displacing 18,750 tons submerged, the Ohio-class boats are the largest submarines ever built for the U.S. Navy. They are also the third-largest subm... | Technology | Naval warfare | null |
22669 | https://en.wikipedia.org/wiki/Open%20cluster | Open cluster | An open cluster is a type of star cluster made of tens to a few thousand stars that were formed from the same giant molecular cloud and have roughly the same age. More than 1,100 open clusters have been discovered within the Milky Way galaxy, and many more are thought to exist. Each one is loosely bound by mutual gravi... | Physical sciences | Stellar astronomy | Astronomy |
22693 | https://en.wikipedia.org/wiki/Operator%20overloading | Operator overloading | In computer programming, operator overloading, sometimes termed operator ad hoc polymorphism, is a specific case of polymorphism, where different operators have different implementations depending on their arguments. Operator overloading is generally defined by a programming language, a programmer, or both.
Rationale ... | Technology | Programming languages | null |
22709 | https://en.wikipedia.org/wiki/Okapi | Okapi | The okapi (; Okapia johnstoni), also known as the forest giraffe, Congolese giraffe and zebra giraffe, is an artiodactyl mammal that is endemic to the northeast Democratic Republic of the Congo in central Africa. However, non-invasive genetic identification has suggested that a population has occurred south-west of the... | Biology and health sciences | Giraffidae | Animals |
22710 | https://en.wikipedia.org/wiki/Ovary | Ovary | The ovary () is a gonad in the female reproductive system that produces ova; when released, an ovum travels through the fallopian tube/oviduct into the uterus. There is an ovary on the left and the right side of the body. The ovaries are endocrine glands, secreting various hormones that play a role in the menstrual cyc... | Biology and health sciences | Reproductive system | null |
22713 | https://en.wikipedia.org/wiki/Opium | Opium | Opium (or poppy tears, scientific name: Lachryma papaveris) is dried latex obtained from the seed capsules of the opium poppy Papaver somniferum. Approximately 12 percent of opium is made up of the analgesic alkaloid morphine, which is processed chemically to produce heroin and other synthetic opioids for medicinal use... | Biology and health sciences | Drugs and pharmacology | null |
22718 | https://en.wikipedia.org/wiki/Ozone | Ozone | Ozone () (or trioxygen) is an inorganic molecule with the chemical formula . It is a pale blue gas with a distinctively pungent smell. It is an allotrope of oxygen that is much less stable than the diatomic allotrope , breaking down in the lower atmosphere to (dioxygen). Ozone is formed from dioxygen by the action of ... | Physical sciences | Chemical elements_2 | null |
22719 | https://en.wikipedia.org/wiki/Orchid | Orchid | Orchids are plants that belong to the family Orchidaceae (), a diverse and widespread group of flowering plants with blooms that are often colourful and fragrant. Orchids are cosmopolitan plants that are found in almost every habitat on Earth except glaciers. The world's richest diversity of orchid genera and species i... | Biology and health sciences | Monocots | null |
22721 | https://en.wikipedia.org/wiki/Obsidian | Obsidian | Obsidian ( ) is a naturally occurring volcanic glass formed when lava extruded from a volcano cools rapidly with minimal crystal growth. It is an igneous rock. Produced from felsic lava, obsidian is rich in the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium. It is commonly found within the m... | Physical sciences | Igneous rocks | Earth science |
22739 | https://en.wikipedia.org/wiki/Obfuscation%20%28software%29 | Obfuscation (software) | In software development, obfuscation is the practice of creating source or machine code that is intentionally difficult for humans or computers to understand. Similar to obfuscation in natural language, code obfuscation may involve using unnecessarily roundabout ways to write statements. Programmers often obfuscate cod... | Technology | Computer security | null |
22773 | https://en.wikipedia.org/wiki/Oxidative%20phosphorylation | Oxidative phosphorylation | Oxidative phosphorylation (UK , US ) or electron transport-linked phosphorylation or terminal oxidation is the metabolic pathway in which cells use enzymes to oxidize nutrients, thereby releasing chemical energy in order to produce adenosine triphosphate (ATP). In eukaryotes, this takes place inside mitochondria. Almo... | Biology and health sciences | Metabolic processes | Biology |
22780 | https://en.wikipedia.org/wiki/Octopus | Octopus | An octopus (: octopuses or octopodes) is a soft-bodied, eight-limbed mollusc of the order Octopoda (, ). The order consists of some 300 species and is grouped within the class Cephalopoda with squids, cuttlefish, and nautiloids. Like other cephalopods, an octopus is bilaterally symmetric with two eyes and a beaked mout... | Biology and health sciences | Mollusks | null |
22799 | https://en.wikipedia.org/wiki/Oxycodone | Oxycodone | Oxycodone, sold under the brand name Roxicodone and OxyContin (which is the extended-release form) among others, is a semi-synthetic opioid used medically for the treatment of moderate to severe pain. It is highly addictive and is a commonly abused drug. It is usually taken by mouth, and is available in immediate-relea... | Biology and health sciences | Pain treatments | Health |
22804 | https://en.wikipedia.org/wiki/Operational%20amplifier | Operational amplifier | An operational amplifier (often op amp or opamp) is a DC-coupled electronic voltage amplifier with a differential input, a (usually) single-ended output, and an extremely high gain. Its name comes from its original use of performing mathematical operations in analog computers.
By using negative feedback, an op amp ci... | Technology | Components | null |
22818 | https://en.wikipedia.org/wiki/Olympus%20Mons | Olympus Mons | Olympus Mons (; ) is a large shield volcano on Mars. It is over high as measured by the Mars Orbiter Laser Altimeter (MOLA), about 2.5 times the elevation of Mount Everest above sea level. It is Mars's tallest volcano, its tallest planetary mountain, and is approximately tied with Rheasilvia on Vesta as the tallest mo... | Physical sciences | Solar System | Astronomy |
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