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Singlestick
Singlestick: traditional ash-wood training stick with basket hilt for backsword and sabre practice, an English 18th-19th-century combat sport, 1904 Olympic event, revived today in HEMA clubs.
SingleStore
SingleStore (formerly MemSQL, founded 2011, Y Combinator W11) is a distributed SQL HTAP database combining in-memory rowstore and on-disk columnstore; MySQL-compatible, C++, owned by Vector Capital since October 2025.
Singlet fission
Singlet fission is a photophysical process where one excited singlet molecule splits into two triplet states, potentially lifting solar cell efficiency past the Shockley–Queisser limit to about 45%.
Singlet fission sensitization of silicon solar cells
Singlet fission sensitization of silicon solar cells places an organic layer that splits one photon's energy into two excitons on silicon, potentially raising its efficiency limit from 29.4% to 34.6%.
Singlet fission solar cells
Singlet fission solar cells are photovoltaic devices that use singlet fission to convert one photon into two charge carriers, pursued mainly as an add-on to silicon cells.
Singlet oxygen
Singlet oxygen is molecular oxygen in an excited singlet state rather than its ordinary triplet ground state, a short-lived reactive oxidant that damages DNA and lipids and drives photodynamic therapy.
Singlet state
The singlet state, also called the spin singlet, is the quantum state of two spin-1/2 particles with total spin zero, and a maximally entangled state that violates Bell inequalities.
Singlet-triplet qubit
The singlet-triplet qubit is a semiconductor spin qubit encoding a logical qubit in the singlet and triplet states of two electrons in a double quantum dot.
Singleton bound
The Singleton bound is an upper limit on the minimum distance of an error-correcting code: a code of length n, dimension k, and distance d satisfies d ≤ n − k + 1.
Singleton pattern
The singleton pattern is a software design pattern that restricts a class to a single instance with a global access point, a mechanism often criticized as hidden global state.
Singleton-Merten dysplasia
Singleton-Merten dysplasia, also known as Singleton-Merten syndrome, is a rare autosomal dominant condition causing abnormal tooth development, thoracic aorta calcification, and osteoporosis, first described in 1973.
Singlish
Singlish, or Colloquial Singapore English, is Singapore's English-based creole contact variety blending English with Malay, Hokkien, Cantonese, and Mandarin; known for particles like lah, opposed by the Speak Good English Movement yet embraced as a national identity marker.
Singlish vocabulary
Singlish vocabulary: words and expressions of Colloquial Singapore English, drawn from Malay, Hokkien, Cantonese, Mandarin, and Tamil, including particles like lah, calques like catch no ball, and OED-listed terms like shiok.
Singrauli
Singrauli is a district in northeastern Madhya Pradesh, India, created from Sidhi district in 2008 and promoted as India's energy capital for its coal mines and power stations.
Singrauli Super Thermal Power Station
Singrauli Super Thermal Power Station is a 2,000 MW coal-fired NTPC power station at Shaktinagar in Sonebhadra district, Uttar Pradesh, whose first unit began generating in 1982.
Singraur Mound
Singraur Mound (Surya Bhita), ASI-protected ancient mound (N-UP-S14) at Singraur village, Soraon tehsil, Prayagraj, Uttar Pradesh; 18 ft high, protected 1920, near the excavated Sringaverapura site.
Singtel
Singtel, or Singapore Telecommunications Limited, is a Singapore telecommunications and technology group tracing its heritage to 1879, majority-owned by Temasek, and the owner of Optus, Australia's second largest telecom provider.
Singular (software)
Singular is a free, open-source computer algebra system for polynomial computations, developed at the University of Kaiserslautern with special emphasis on commutative algebra, algebraic geometry, and singularity theory.
Singular homology
Singular homology is a construction in algebraic topology that assigns to every topological space abelian groups measuring its connectedness and holes, defined by Samuel Eilenberg in 1944.
Singular matrix
A singular matrix, also known as a degenerate matrix, is a square matrix with determinant zero and no multiplicative inverse, so Ax = b may lack a unique solution.
Singular series
The singular series is an Euler product over primes, chiefly in the Hardy–Littlewood prime k-tuple conjecture and circle method, correcting a naive random model for local obstructions.
Singular solution
A singular solution of a differential equation is a solution not obtainable from the general solution by assigning any value to its arbitrary constant, such as the envelope of Clairaut's equation.
Singular spectrum analysis
Singular spectrum analysis (SSA) is a nonparametric method, describable as PCA applied to time series, that decomposes a series into trend, oscillations, and noise for denoising, forecasting, and trend extraction.
Singular they
Singular they: use of the English pronoun they/them/their for one person, either of unknown gender or as a nonbinary person's pronoun. Attested since 1375, endorsed by APA and MLA, Merriam-Webster's 2019 Word of the Year.
Singular value
A singular value of a matrix or linear operator is a non-negative real number measuring how much it stretches space; singular values form the singular value decomposition.
Singular value decomposition
The singular value decomposition (SVD) is a factorization of any real or complex matrix A into A = U Σ Vᵀ, with orthogonal matrices and nonnegative singular values.
Singular value thresholding
Singular value thresholding (SVT) is a first-order iterative algorithm for minimizing the nuclear norm of a matrix, introduced by Cai, Candès, and Shen in 2010, whose leading application is matrix completion.
Singularities of parallel manipulators
A singularity of a parallel manipulator is a configuration where a Jacobian matrix loses rank, so the mechanism gains or loses degrees of freedom and control degenerates.
Singularity
In mathematics, a singularity, or singular point, is a point where an equation, surface, or mapping blows up, fails to be defined, or becomes degenerate.
Singularity analysis
Singularity analysis is a technique of analytic combinatorics, presented by Philippe Flajolet and Andrew Odlyzko in 1990, that derives asymptotic estimates of a generating function's coefficients from its dominant singularities.