All articles starting with E
17,681 articles
External sorting
External sorting, also called external sort, sorts data too large for main memory by moving blocks between memory and storage, typically via external merge sort.
External validity
External validity is the extent to which a study's findings, especially its causal inferences, apply to populations, settings, and times beyond the study sample, complementing internal validity.
External-cavity diode laser
An external-cavity diode laser (ECDL) is a tunable semiconductor laser whose external feedback element, usually a diffraction grating, narrows the linewidth and enables broad tuning.
Externality
An externality, plural externalities, is a cost or benefit of one agent's action that falls on third parties outside the market transaction and is not compensated through market prices.
Externalizing disorder
An externalizing disorder is a mental disorder involving outward-directed behavior such as aggression, impulsivity, and rule breaking, spanning conditions like ADHD, conduct disorder, and antisocial personality disorder.
Exterritorial
Exterritorial is a 2025 German-language Netflix action thriller by Christian Zübert, starring Jeanne Goursaud as an ex-special forces soldier whose son vanishes in the US consulate in Frankfurt; it drew 87.5 million views in H1 2025.
Extince
Extince, the stage name of Peter Kops, is a Dutch rapper and founding figure of Nederhop, best known for "Spraakwater" (1995), the first Dutch-language rap song to reach the charts.
Extinct (film)
Extinct (2021) is a Chinese-American-Canadian animated comedy directed by David Silverman and Raymond S. Persi, about flummels Op and Ed time-traveling from 1835 Galápagos to modern Shanghai; released theatrically in 2021 and on Netflix November 19, 2021.
Extinct arthropods of North America
Extinct arthropods of North America: trilobites of Laurentia (521 to 252 million years ago, over 22,000 species), Burgess Shale-type soft-bodied Cambrian arthropods, giant Arthropleura, eurypterids, and Quaternary insects from caves and packrat middens.
Extinct in the wild
Extinct in the Wild (EW) is an IUCN Red List category for species surviving only in captivity, cultivation, or naturalized populations outside their past range; 73 species held the status in 2019, with recoveries including Arabian oryx and scimitar-horned oryx.
Extinct language
An extinct language has no remaining native speakers and no everyday use, typically after language shift to a dominant majority language; related terms include dead, moribund, dormant, and sleeping languages.
Extinct stony coral genera
Extinct stony coral genera: extinct genera of Scleractinia, aragonite-skeletoned corals first appearing ~241 Myr; ~30% of Maastrichtian genera died out at the K-T boundary, with deep-water, cosmopolitan, non-symbiotic, solitary genera surviving.
Extinction
Extinction: the permanent disappearance of a species or taxon. Covers background versus mass extinction, the Big Five events, Cuvier's 1812 proof, IUCN assessment, and the contested sixth mass extinction.
Extinction (2018 film)
Extinction (2018) is an American sci-fi action film directed by Ben Young, starring Michael Peña and Lizzy Caplan, released on Netflix July 27, 2018 after Universal dropped it; its twist reveals the invaders are humans reclaiming Earth from memory-implanted androids.
Extinction (astronomy)
Extinction, also called interstellar extinction, is the dimming of starlight by interstellar dust, which absorbs and scatters light and reddens stars. It was discovered by Robert Trumpler in 1930.
Extinction coefficient
The extinction coefficient is a per-path-length measure of how strongly a medium attenuates a wave through absorption and scattering, used in chemistry, atmospheric science, and optics.
Extinction event
Extinction event (mass extinction): a geologically short interval when at least 75% of species die out. Five Big Five events in 500 million years; a debated human-driven sixth is under discussion.
Extinction events in rugose and tabulate coral history
Extinction events in rugose and tabulate coral history: end-Ordovician, Late Devonian (Kellwasser), Carboniferous, and end-Permian crises that shaped and finally eliminated the Paleozoic Rugosa and Tabulata.
Extinction learning
Extinction learning is the decline of a conditioned response when the conditioned stimulus is repeatedly presented without reinforcement; it underlies exposure therapy, and the original association survives, causing relapse.
Extinction probability of branching processes
The extinction probability of a branching process is the probability that a population dies out, equal to the smallest fixed point of the offspring generating function.
Extinction Rebellion
Extinction Rebellion (XR) is a decentralized international climate movement founded in the United Kingdom in 2018 that uses nonviolent mass civil disobedience to demand government action on climate change.
Extinction risk from climate change
Extinction risk from climate change, also known as species extinction from global warming, is the likelihood that a changing climate drives species or ecosystems extinct, projected to rise steeply with warming.
ExTINGUISH trial
ExTINGUISH (NCT04372615) is the first NIH-funded phase 2B randomized, double-blind, placebo-controlled trial of inebilizumab 300 mg, an anti-CD19 antibody, added to first-line therapy in 116 participants aged 12+ with moderate-to-severe anti-NMDAR encephalitis, primary endpoint mRS change at 16 weeks.
Extirpation of idolatries
The extirpation of idolatries (Spanish: extirpación de idolatrías) was a colonial Spanish campaign to destroy indigenous religions as idolatry, chiefly in the viceroyalty of Peru from 1532.
Extol
Extol is a Norwegian extreme metal band formed in 1993 in Bekkestua near Oslo, known for fusing technical death metal, thrash, and progressive elements with lyrics informed by the members' Christian faith.
Extortion
Extortion: obtaining property or benefit through threats, legally distinct from blackmail; at common law an officials' offense, now covered by the Hobbs Act and 18 U.S.C. 873, and a top FBI-reported cybercrime via ransomware and sextortion.
eXTP
eXTP (enhanced X-ray Timing and Polarimetry mission, 增强型X射线时变与偏振空间天文台) is a Chinese-led X-ray observatory with European partners, approved for launch in 2030 to study neutron stars and black holes.
Extra 300
The Extra 300 is a German two-seat aerobatic monoplane designed by competition pilot Walter Extra, first flown in 1988 and powered by a 300 hp Lycoming engine.
Extra Credits
Extra Credits: educational YouTube channel of animated video essays on game design and history, founded by Daniel Floyd and James Portnow (2008); known for tangential learning, Extra History, and divided critical reception.
Extra Geography
Extra Geography is a 2026 British coming-of-age comedy-drama, Molly Manners' feature debut, adapted from Rose Tremain's 2007 short story by Miriam Battye. It premiered in Sundance's World Cinema Dramatic Competition and stars Marni Duggan, Galaxie Clear, and Alice Englert.