All articles starting with S
44,216 articles
Sigismund, Archduke of Austria
Sigismund of Habsburg was a Habsburg prince who ruled Tyrol from 1446 to 1490. He was known as "the Rich in Coin" for reforming the coinage.
Sigismund, Holy Roman Emperor
Sigismund of Luxembourg (c. 1368–1437), last Luxembourg Holy Roman Emperor, crowned by Pope Eugene IV in Rome 1433; also King of Hungary (1387), King of the Romans (1410), and King of Bohemia (1419), convener of the Council of Constance.
Sigita Strecen Mazeikaite
Sigita Mažeikaitė-Strečen (Sigita Strecen Mazeikaite), born 1958 in Panevėžys, Lithuanian handball player; 1980 Moscow Olympic gold and 1982 world champion with the USSR team, Eglė Vilnius club player, later coach in Germany.
Sigitas Geda
Sigitas Geda (1943–2008) was a Lithuanian poet, playwright, and translator who published over 50 poetry collections, translated Dante and the Quran into Lithuanian, and helped lead the Sąjūdis reform movement that restored Lithuania's independence.
Sigitas Parulskis
Sigitas Parulskis, born 1965 in Obeliai, Lithuania, is a poet, novelist, playwright, and critic, best known for Darkness and Partners, the first Lithuanian novel on Lithuanian complicity in the Holocaust.
Sigla
Sigla is a London-based private equity firm investing in healthcare and business services companies across Europe. It was founded in 2025 by Philipp Lesjak and Karl Geisel.
SIGLEC1
SIGLEC1 encodes Siglec-1, sialoadhesin, CD169: a 185 kDa macrophage-restricted sialic acid-binding lectin with 17 Ig domains, no signaling motif, interferon-inducible, binding HIV-1, SARS-CoV-2, and Ebola virus.
SigLIP (sigmoid loss for language-image pretraining)
SigLIP is a method for training paired image-text models that replaces CLIP's softmax contrastive loss with a pairwise sigmoid loss, introduced at Google and published at ICCV 2023.
Siglos
The siglos (سیگلوس) was the silver coin of the Achaemenid Empire, introduced by Darius I in the late sixth century BCE and struck with the king as an archer.
Sigma
Sigma (Σ, σ, ς) is the 18th letter of the Greek alphabet, representing /s/, derived from Phoenician shin with numeral value 200; rival letter san, lunate and final forms, and Unicode encodings distinguish it.
Sigma (DJs)
Sigma (DJs) are a British drum and bass duo, Cameron Edwards and Joe Lenzie, formed 2006 in Leeds; UK No. 1 hits "Nobody to Love" and "Changing" (2014), albums Life, Hope, London Sound, and DAY ONE on their Day Ones imprint.
SIGMA 155
SIGMA 155, known in Israel as the Ro'em, is a fully automatic 155 mm self-propelled howitzer developed by Elbit Systems for the Israel Defense Forces, entering combat in 2026.
Sigma Alpha Epsilon (ΣΑΕ)
Sigma Alpha Epsilon (ΣΑΕ, SAE) is a men's college social fraternity founded March 9, 1856 at the University of Alabama, the only major national fraternity originating in the Deep South, with 209 US chapters, 375,000+ initiates, headquarters at the Levere Memorial Temple in Evanston, Illinois, and a documented history of hazing controversies and reforms.
Sigma bond
A sigma bond (σ bond) is a covalent bond formed by head-on overlap of atomic orbitals along the internuclear axis, and every single covalent bond is one.
Sigma Boötis
Sigma Boötis (σ Boo) is an F-type main-sequence star in the constellation Boötes, about 52 light-years away, slightly hotter and more massive than the Sun.
Sigma Boy (Сигма Бой)
Sigma Boy (Сигма Бой) is a viral Russian pop-EDM song released October 2024 by child singers Betsy and Maria Yankovskaya, written by Mikhail Chertishchev; it hit No. 7 on Billboard Hot Dance/Pop Songs and sparked EU and Russian controversy.
Sigma Chi (ΣΧ)
Sigma Chi (ΣΧ) is an international social fraternity founded June 28, 1855 at Miami University in Oxford, Ohio by seven former Delta Kappa Epsilon members, with over 255,000 living members, Evanston, Illinois headquarters, and a documented record of chapter hazing sanctions.
Sigma Computing
Sigma Computing is a San Francisco company founded in 2014 by Rob Woollen and Jason Frantz whose Sigma platform is a spreadsheet UI on cloud data warehouses like Snowflake and Databricks, compiling formulas into live SQL with writeback, AI apps, and embedding.
Sigma Coronae Borealis
Sigma Coronae Borealis (σ CrB) is a quintuple star system in Corona Borealis about 69 light-years from Earth, with two Sun-like stars orbiting every 1.14 days.
Sigma Draconis
Sigma Draconis, formally named Alsafi, is a K-type main-sequence star in the constellation Draco about 19 light years from the Sun, faintly visible to the naked eye.
Sigma factor
Sigma factor (σ factor): bacterial protein that binds RNA polymerase core enzyme to form the holoenzyme, recognizes promoters, and initiates transcription; includes housekeeping σ70 and alternative σ factors regulated by anti-sigma factors.
Sigma Gamma Rho
Sigma Gamma Rho Sorority, Inc. (ΣΓΡ), a historically Black sorority of the Divine Nine, founded November 12, 1922 at Butler University, Indianapolis, by seven educators; incorporated 1929, joined NPHC 1937, slogan "Greater Service, Greater Progress."
Sigma Geminorum
Sigma Geminorum is a bright RS Canum Venaticorum binary star in Gemini, consisting of a magnetically active K1 giant and an unseen companion in a roughly 19.6-day orbit.
Sigma Healthcare
Sigma Healthcare is an Australian full-line pharmaceutical wholesaler and pharmacy franchisor founded in Melbourne in 1912; it completed a merger with Chemist Warehouse Group in February 2025.
Sigma Nu
Sigma Nu (ΣΝ) is a men's college social fraternity founded January 1, 1869 at Virginia Military Institute by Hopkins, Quarles, and Riley as the anti-hazing Legion of Honor, with over 150 chapters and 270,000 initiates.
Sigma Octantis
Sigma Octantis, officially named Polaris Australis, is a faint yellow-white giant star in Octans and the closest naked-eye star to the south celestial pole, though at magnitude 5.47 it is too dim for navigation.
Sigma Orionis
Sigma Orionis is a multiple star system of at least five components just below Orion's Belt, whose radiation illuminates the Horsehead Nebula, with a surrounding young cluster.
Sigma Orionis cluster
The Sigma Orionis cluster is a young star cluster around the multiple star Sigma Orionis, below Orion's Belt, containing about 700 stars, brown dwarfs, and planetary-mass objects.
Sigma Phi Delta
Sigma Phi Delta (ΣΦΔ) is an international professional-social fraternity for engineering students, founded on April 11, 1924, at the University of Southern California and admitting only students seeking engineering degrees.
Sigma Phi Epsilon
Sigma Phi Epsilon (SigEp), national social fraternity founded November 1, 1901 at Richmond College (now University of Richmond) by 12 men including Carter Ashton Jenkens; known for the 1991 Balanced Man Program and over 15,000 undergraduates.