- S-duality
- Sabermetrics
- Saccheri quadrilateral
- Saddle
- Saddle point
- Saddle point approximation
- Saddle point method
- Saddle surface
- Saddle-node bifurcation
- Safe
- Safe prime
- Sagitta
- Saint Andrew's Cross or Saint Andrew's cross
- Saint Anthony's Cross or Saint Anthony's cross
- Saint Petersburg Paradox or Saint Petersburg paradox
- Sal
- Salem number
- Salesman problem
- Samaritan
- Sample
- Sample mean
- Sample median
- Sample size
- Sample Space or Sample space
- Sample variance
- Sampling
- Sampling function
- Sampling theorem
- Sampling theory
- Sandwich theorem
- Sangaku problem
- Sarah Flannery
- Sard theorem
- Sard's theorem
- Sarrus linkage
- SAS or Sas
- Sasakian manifold
- Satellite knot
- Satisfaction
- Satisfiability problem
- Satisfiable
- Saturate
- Saturated
- Savitzky-Golay filter
- Savoy knot
- Sawtooth wave
- Sc
- Scalar
- Scalar curvature
- Scalar field
- Scalar function
- Scalar matrix
- Scalar multiplication
- Scalar Potential or Scalar potential
- Scalar product
- Scalar triple product
- Scalar-valued function
- Scale
- Scale factor
- Scale invariance
- Scale parameter
- Scale-free network
- Scale-space theory
- Scalene triangle
- Scaling
- Scarabaeus
- Scatter diagram
- Scatter plot
- Scattering matrix
- Scattering theory
- Scatterplot
- Scenario
- Sceptic
- Schanuel's conjecture
- Schauder basis
- Schauder fixed point theorem
- Scheduling theory
- Schema
- Scheme
- Scherk surface
- Schiffler point
- Schinzel's hypothesis
- Schinzel's hypothesis H
- Schlicht function
- Schlicht functions
- Schläfli symbol
- Schmidt's theorem
- Schnirelmann constant
- Schnirelmann density
- Schock Prize or Schock prize
- Schoen-Yau conjecture or Schoen-yau conjecture
- Scholz Conjecture or Scholz conjecture
- Schoof's algorithm
- Schoof-Elkies-Atkin algorithm
- Schoolgirl problem
- Schottky problem
- Schouten-Nijenhuis bracket
- Schreier refinement theorem
- Schröder's equation
- Schröder-Bernstein Theorem or Schröder-Bernstein theorem
- Schrödinger equation or Schrödinger Equation
- Schrödinger's wave equation
- Schubert calculus
- Schubert cell
- Schubert cycle
- Schubert variety
- Schur complement
- Schur decomposition
- Schur function
- Schur functor
- Schur lemma
- Schur multiplicator
- Schur multiplier
- Schur orthogonality relations
- Schur polynomial
- Schur theorem
- Schur's inequality
- Schur's lemma or Schur's Lemma
- Schur's theorem
- Schwartz function
- Schwartz space
- Schwartz's kernel theorem
- Schwartz-Bruhat function
- Schwarz lemma
- Schwarz reflection principle
- Schwarz triangle
- Schwarz's inequality
- Schwarz's lemma
- Schwarz-Christoffel mapping
- Schwarzian derivative
- Schwarzschild geometry
- Schwarzschild metric
- Schwarzschild solution
- Schönflies theorem
- Scientific calculator
- Scientific notation or Scientific Notation
- Scintillating grid illusion
- Score function
- Scott continuous
- Scott topology
- Screw
- Scruple
- Sd
- Search algorithm or Search Algorithm
- Search problem
- Search tree
- Searching
- Seashell
- Sec
- Secant
- Secant line
- Secant method
- Secant Number or Secant number
- Sech
- Second
- Second countable
- Second countable space
- Second derivative test
- Second fundamental form
- Second fundamental tensor
- Second Group Isomorphism Theorem or Second group isomorphism theorem
- Second isomorphism theorem
- Second ring isomorphism theorem
- Second-countable space
- Second-order arithmetic
- Second-order logic
- Secretary problem
- Section
- Section of a fiber bundle
- Sectional curvature
- Sector
- Secular equation
- Seed or SEED
- Seed of Life or Seed of life
- Seek time
- Segment
- Segre classification
- Segre imbedding
- Segre map
- Seifert conjecture
- Seifert fiber space
- Seifert fibration
- Seifert manifold
- Seifert matrix
- Seifert surface
- Selberg trace formula
- Selberg zeta function
- Selection sort
- Selector
- Self number
- Self-adjoint
- Self-adjoint operator
- Self-avoiding polygon
- Self-avoiding walk
- Self-descriptive number
- Self-dual
- Self-dual polyhedron
- Self-linking number
- Self-loop
- Self-similarity
- Selfridge's conjecture
- Selmer group
- Semantics
- Semi-continuous
- Semi-continuous function
- Semi-continuous mapping
- Semi-cubic parabola
- Semi-definite form
- Semi-direct product
- Semi-group
- Semi-lattice
- Semi-local ring
- Semi-locally simply connected
- Semi-Markov process
- Semi-norm
- Semi-regular polyhedra
- Semi-ring
- Semi-simple algebra
- Semi-simple group
- Semi-simple Lie algebra
- Semi-simple Lie group
- Semi-simple module
- Semi-simple ring
- Semicircle
- Semicolon
- Semicolon derivative
- Semicontinuous
- Semicubical parabola
- Semidefinite programming
- Semiderivative
- Semidirect product
- Semifield
- Semigroup
- Semigroup ring
- Semihereditary ring
- Semilattice
- Semilatus Rectum or Semilatus rectum
- Semilocal ring
- Semilocally simply connected
- Semimajor Axis or Semimajor axis
- Semimetric
- Semiminor axis
- Seminorm
- Semiperfect magic cube
- Semiperfect number
- Semiperimeter
- Semiprime
- Semiprime ring
- Semiprimitive ring
- Semiregular polyhedron
- Semiring
- Semisimple algebra
- Semisimple group
- Semisimple Lie algebra
- Semisimple Lie group
- Semisimple ring
- Semisymmetric graph
- Sense-preserving mapping
- Sensitivity
- Sentence
- Sentence (mathematical logic)
- Sentential calculus
- Sentential formula
- Sentential variable
- Separable
- Separable closure
- Separable extension
- Separable polynomial
- Separable space
- Separated
- Separated scheme
- Separated sets
- Separation
- Separation axiom
- Separation axioms
- Separation of variables or Separation of Variables
- Separation theorem
- Separatrix
- Septagon
- Septendecillion
- Septillion
- Sequence
- Sequence of series
- Sequent
- Sequent calculus
- Sequential analysis
- Sequential probability ratio test
- Sequential space
- Sequentially compact
- Sequentially continuous
- Sequentially-compact space
- Series
- Series (mathematics)
- Series expansion
- Series reversion
- Series term
- Series-parallel graph
- Series-parallel network
- Serpentine curve
- Serre duality
- Serre fibration
- Serre subcategory
- Serre's conjecture
- Serret-Frenet equations
- Serret-Frenet formulas
- Service
- Sesquilinear form
- Set
- Set closure
- Set difference
- Set direct product
- Set extension
- Set modulus
- Set partition
- Set system of finite character
- Set theory or Set Theory
- Seven
- Seven Bridges of Königsberg or Seven bridges of Königsberg
- Seven bridges problem
- Seven-segment display
- Seventeen or Bust or Seventeen or bust
- Several complex variables
- Sexagesimal
- Sexdecillion
- Sextic equation
- Sextillion
- Sexy primes
- Sgn
- Sh
- Shadow
- Shah function
- Shanks-Tonelli algorithm
- Shannon entropy
- Shannon sampling theorem
- Shannon theorem
- Shannon's entropy
- Shannon's noiseless coding theorem
- Shape operator
- Shape theory
- Shapiro inequality
- Shapley value
- Sharing
- Sharkovskii's theorem
- Sharkovsky's theorem
- Sharpe Ratio or Sharpe ratio
- Sharply multiply transitive
- Shaw Prize
- Sheaf
- Sheaf (mathematics)
- Sheaf cohomology
- Sheaf theory
- Sheafification
- Shear mapping
- Shear matrix
- Sheet
- Sheffer polynomial
- Sheffer sequence
- Sheffer Stroke or Sheffer stroke
- Sheila Scott Macintyre or Sheila scott macintyre
- Shell
- Shell theory
- Shellsort
- Shephard's problem
- Sherman-Morrison Formula or Sherman-Morrison formula
- Shi
- Shift
- Shift operator
- Shift transformation
- Shimura curve
- Shimura variety
- Shimura-Taniyama conjecture
- Shimura-Taniyama-Weil conjecture
- Shoe
- Shogi
- Shooting method
- Short exact sequence
- Short five lemma
- Shortening
- Shortest path
- Shortest path problem
- Shri Dattathreya Ramachandra Kaprekar
- Shuffle
- Shunting yard algorithm
- Shur's inequality
- Si-ci-spiral
- Siamese dodecahedron
- Sibling
- Sicherman dice
- Sici spiral
- Side
- Sidereal year
- Siegel disc
- Siegel modular form
- Siegel theorem
- Siegel's theorem
- Siegel's upper half-space
- Sierpinski carpet
- Sierpinski constant
- Sierpinski Curve or Sierpinski curve or Sierpiński curve
- Sierpinski gasket or Sierpiński gasket
- Sierpinski numbers
- Sierpinski Problem or Sierpinski problem
- Sierpinski sieve
- Sierpinski space
- Sierpinski sponge
- Sierpinski Triangle or Sierpinski triangle
- Sierpiński game
- Sieve
- Sieve method
- Sieve of Eratosthenes or Sieve of eratosthenes
- Sigma
- Sigma additivity
- Sigma function
- Sigma-algebra
- Sigma-compact topological space
- Sigma-compactness
- Sigma-finite
- Sigmoid
- Sigmoid curve
- Sigmoid function
- Sign
- Sign test
- Signal-to-noise ratio
- Signature
- Signature of a manifold
- Signed measure
- Significance
- Significance arithmetic
- Significance level
- Significance test
- Significant digits
- Significant figure
- Significant Figures or Significant figures
- Signpost
- Signum
- Signum function
- Silver mean
- Silver number
- Silver ratio
- Silver rectangle
- Silverman-Toeplitz theorem
- SIMD
- Similar
- Similar matrices
- Similar matrix
- Similar triangles
- Similarity
- Similarity transformation
- Simon Donaldson or Simon donaldson
- Simple algebra
- Simple continued fraction
- Simple directed graph
- Simple extension
- Simple field extension
- Simple finite group
- Simple function
- Simple graph
- Simple group
- Simple Harmonic Motion or Simple harmonic motion
- Simple Harmonic Oscillator or Simple harmonic oscillator
- Simple interest
- Simple Lie algebra
- Simple Lie group
- Simple module
- Simple path
- Simple pole
- Simple polygon
- Simple program
- Simple random sample
- Simple ring
- Simple root
- Simple set
- Simple zero
- Simplex
- Simplex (abstract)
- Simplex algorithm or Simplex Algorithm
- Simplex method
- Simplicial approximation theorem
- Simplicial category
- Simplicial complex or Simplicial Complex
- Simplicial homology
- Simplicial object
- Simplicial set
- Simplicity
- Simply connected
- Simply transitive
- Simpson formula
- Simpson's formulas
- Simpson's paradox
- Simpson's rule or Simpson's Rule
- Simson line
- Simson straight line
- Simson's line
- Simula
- Simulated Annealing or Simulated annealing
- Simultaneous equations
- Sin
- Sinai billiards
- Sinc
- Sinc function
- Sine
- Sine integral
- Sine theorem
- Sine-Gordon equation
- Sines Law
- Single-valued function
- Singleton (mathematics)
- Singleton set
- Singly even number
- Singular
- Singular distribution
- Singular function
- Singular homology
- Singular Integral or Singular integral
- Singular matrix
- Singular measure
- Singular point
- Singular set
- Singular solution
- Singular support
- Singular value
- Singular value decomposition or Singular Value Decomposition
- Singular values
- Singularity
- Sinh
- Sinh-Gordon equation
- Sinusoid
- Sinusoidal projection
- Sir Arthur Schuster
- SIR Model
- Site
- Siteswap
- Six
- Skein relationship
- Skeleton
- Skew
- Skew field
- Skew Hermitian matrix
- Skew lines
- Skew polygon
- Skew Polyhedron or Skew polyhedron
- Skew Polyomino or Skew polyomino
- Skew symmetric matrix
- Skew-field
- Skew-Hermitian matrix
- Skew-symmetric bilinear form
- Skew-symmetric matrix
- Skewes number
- Skewes' number
- Skewness
- Sklar's theorem
- Skolem function
- Skolem paradox
- Skolem-Noether theorem
- Skolemization
- Skorokhod topology
- Skyrme field
- SL or Sl
- Slack variable
- Slant height
- Slash
- Slavic numerals
- Slice knot
- Slide Rule or Slide rule
- Slightly defective number
- Slinky
- Slip Knot or Slip knot
- Slit
- Slope
- Slope field
- Slothouber-Graatsma Puzzle or Slothouber-Graatsma puzzle
- Smale horseshoe map
- Smale's h-cobordism theorem
- Smale's problems
- Small category
- Small circle
- Small cubicuboctahedron
- Small ditrigonal dodecicosidodecahedron
- Small ditrigonal icosidodecahedron
- Small dodecahemicosahedron
- Small dodecahemidodecahedron
- Small dodecicosahedron
- Small dodecicosidodecahedron
- Small icosicosidodecahedron
- Small icosihemidodecahedron
- Small number
- Small retrosnub icosicosidodecahedron
- Small rhombicosidodecahedron
- Small rhombicuboctahedron
- Small rhombidodecahedron
- Small rhombihexahedron
- Small snub icosicosidodecahedron
- Small Stellated Dodecahedron or Small stellated dodecahedron
- Small stellated truncated dodecahedron
- Small world network
- Smith Brothers or Smith brothers
- Smith conjecture
- Smith normal form
- Smith number
- Smooth function
- Smooth manifold
- Smooth map
- Smooth morphism
- Smooth number
- Smooth structure
- Smooth surface
- Smoothing
- Sn
- Snake
- Snake Eyes or Snake eyes
- Snake lemma
- Snark
- SNCF metric
- Snedecor's F-distribution
- Snell's law
- Snobol
- Snowflake
- Snub cube
- Snub cuboctahedron
- Snub disphenoid
- Snub dodecadodecahedron
- Snub dodecahedron
- Snub icosidodecadodecahedron
- Snub polyhedron
- Snub square antiprism
- SO or So
- Soap bubble
- Sober space
- Sobolev classes (of functions)
- Sobolev inequality
- Sobolev space
- Soccer ball
- Sociable numbers
- Social choice
- Social choice theory
- Social network theory
- Socle
- Socrates
- Socrates Scholasticus
- Soddy's hexlet
- Sofia Kovalevskaya
- Soft sheaf
- Software
- Sofya Yanovskaya
- Sohcahtoa or SOHCAHTOA
- Sol geometry
- Solar system or Solar System
- Soldner's constant
- Solenoid
- Solenoidal field
- Solid
- Solid angle
- Solid Geometry or Solid geometry
- Solid of revolution
- Solidus
- Solitary number
- Soliton
- Solovay-Strassen test
- Solstice
- Soluble by radicals
- Soluble group
- Solv manifold
- Solv manifold, compact or Compact solv manifold or Compact Solv manifold
- Solvable group
- Solvable Lie algebra
- Solvable Lie group
- SOMA or Soma
- Soma cube
- Somer-Lucas pseudoprime
- Somos's quadratic recurrence constant
- Son
- Sophie Germain or Sophie germain
- Sophie Germain prime
- Sophist
- Sophomore's dream
- SOR method
- Sorgenfrey line
- Sorgenfrey plane
- Sorites Paradox or Sorites paradox
- Sorting
- Sosigenes
- Source
- Souslin's hypothesis
- South Pole or South pole
- Space
- Space curve
- Space diagonal
- Space forms
- Space groups
- Space-filling curve
- Space-filling function
- Space-filling polyhedron
- Space-time
- Spacelike
- Span
- Spanier-Whitehead duality
- Spanning Tree or Spanning tree
- Spanning tree (mathematics)
- Sparkline
- Sparse matrix
- Sparsely totient number
- Spearman rank correlation coefficient
- Specht module
- Special function
- Special functions
- Special Jordan algebra
- Special linear group
- Special orthogonal group
- Special orthogonal matrix
- Special point
- Special unitary group
- Special unitary matrix
- Specialization
- Species
- Specific conductivity
- Specificity
- Spectral analysis
- Spectral asymmetry
- Spectral density
- Spectral measure
- Spectral norm
- Spectral power density
- Spectral radius
- Spectral resolution
- Spectral sequence
- Spectral set
- Spectral theorem
- Spectral theory
- Spectral theory of compact operators
- Spectral theory of differential operators
- Spectral type
- Spectrum
- Spectrum of a matrix
- Spectrum of a ring
- Spectrum of an operator
- Spectrum sequence
- Speed
- Speedup
- Spence's function
- Sperner family
- Sperner lemma
- Sperner system
- Sperner theorem
- Sperner's lemma or Sperner's Lemma
- Sperner's theorem
- Speusippus
- Sphenic number
- Sphenocorona
- Sphenoid
- Sphenomegacorona
- Sphere
- Sphere bundle
- Sphere eversion
- Sphere packing
- Sphere theorem
- Spherical
- Spherical aberration or Spherical Aberration
- Spherical Bessel differential equation
- Spherical Bessel function or Spherical bessel function
- Spherical Bessel function of the first kind
- Spherical Bessel function of the second kind
- Spherical Bessel function of the third kind
- Spherical cap
- Spherical cone
- Spherical coordinates
- Spherical design
- Spherical distance
- Spherical excess
- Spherical functions
- Spherical geometry
- Spherical Hankel function of the first kind
- Spherical Hankel function of the second kind
- Spherical Harmonic or Spherical harmonic
- Spherical harmonics
- Spherical mean
- Spherical Mirror or Spherical mirror
- Spherical modified Bessel function of the first kind
- Spherical packing
- Spherical polar coordinates
- Spherical polygon
- Spherical polyhedron
- Spherical symmetry
- Spherical triangle
- Spherical trigonometry
- Sphericon
- Spheroid
- Spheroidal coordinates
- Spheroidal function
- Spheroidal harmonic
- Sphinx
- Spider
- Spieker circle
- Spigot algorithm
- Spikey
- Spiky
- Spin
- Spin group
- Spindle
- Spindle torus
- Spinode
- Spinor
- Spinor field
- Spinor group
- Spinor representation
- Spira mirabilis
- Spiral
- Spirals
- Spiric section
- Spirograph
- Splay tree
- Spline
- Spline interpolation
- Split
- Split exact sequence
- Split short exact sequence
- Splitter
- Splitting
- Splitting field
- Spoke
- Sponge
- Sporadic group
- Sporadic simple group
- Sports
- Spray
- Springer representation
- Spur
- Sqrt
- Squarable
- Square
- Square antiprism
- Square bracket
- Square cupola
- Square dipyramid
- Square grid
- Square gyrobicupola
- Square integrable
- Square knot
- Square matrix
- Square number
- Square orthobicupola
- Square packing
- Square Polyomino or Square polyomino
- Square Prism or Square prism
- Square pyramid
- Square pyramidal number
- Square root or Square Root
- Square root of 2
- Square root of 3
- Square root of 5
- Square root of polynomial
- Square the circle
- Square tiling
- Square triangular number
- Square Wave or Square wave
- Square Window
- Square-free
- Square-free number
- Squared
- Squared square
- Squarefree
- Squarefree factorization
- Squarefree word
- Squaring
- Squaring the circle
- Squeeze rule
- Squeezing theorem
- Srinivasa Ramanujan or Srinivasa ramanujan
- SSA
- St. Ives problem
- Stability
- Stability criterion
- Stability matrix
- Stability theory
- Stabilization
- Stabilizer
- Stable distribution
- Stable fixed point
- Stable manifold
- Stable manifold theorem
- Stable marriage problem or Stable Marriage Problem
- Stable polynomial
- Stack
- Stadium
- Stair function
- Staircase function
- Stalk
- Stalk of a sheaf
- Standard basis
- Standard deviation or Standard Deviation
- Standard error
- Standard map
- Standard normal distribution
- Standard simplex
- Standard tori
- Standardized moment
- Standardized score
- Stanley-Wilf conjecture
- Stanton number
- Star
- Star convex
- Star figure
- Star number
- Star of a function element
- Star of David or Star of david
- Star of Lakshmi
- Star polygon
- Star polyhedron
- Star product
- Star refinement
- Stark conjecture
- Stark's conjecture
- State
- State diagram
- State space
- Statics
- Stationary distribution
- Stationary phase formula
- Stationary point
- Stationary process
- Stationary set
- Stationary stochastic process
- Stationary value
- Statistic
- Statistical Analysis or Statistical analysis
- Statistical correlation
- Statistical Dispersion or Statistical dispersion
- Statistical distribution
- Statistical ensemble
- Statistical estimation
- Statistical estimator
- Statistical hypothesis
- Statistical independence
- Statistical mechanics or Statistical Mechanics
- Statistical model
- Statistical modelling
- Statistical power
- Statistical quality control
- Statistical Range or Statistical range
- Statistical test
- Statistics
- Steenrod algebra
- Steenrod five lemma
- Steenrod operation
- Steenrod reduced power
- Steenrod square
- Steenrod-Eilenberg Axioms or Steenrod-Eilenberg axioms
- Stefan condition
- Stefan problem
- Stefan-Boltzmann law
- Stein manifold
- Stein space
- Steinberg group
- Steinberg module
- Steiner point
- Steiner points
- Steiner problem
- Steiner surface
- Steiner system
- Steiner tree
- Steiner tree problem
- Steiner triple system
- Steiner's Problem or Steiner's problem
- Steiner's theorem
- Steinhaus-Moser notation
- Steinmetz solid
- Stella octangula
- Stellated octahedron
- Stellated truncated hexahedron
- Stellation
- Stem-and-leaf diagram
- Step
- Step function
- Steradian
- Stereogram
- Stereographic projection
- Stereology
- Stern prime
- Stern-Brocot tree
- Stevedore's knot
- Stewart's theorem or Stewart's Theorem
- Stickelberger's theorem
- Stiefel manifold
- Stiefel-Whitney class or Stiefel-whitney class
- Stiefel-Whitney number
- Stieltjes constants
- Stieltjes Integral or Stieltjes integral
- Stieltjes moment problem
- Stiff Differential Equation or Stiff differential equation
- Stirling formula
- Stirling number of the first kind
- Stirling number of the second kind
- Stirling numbers of the first kind
- Stirling numbers of the second kind
- Stirling polynomial
- Stirling transform
- Stirling's approximation
- Stirling's formula
- Stirling's series
- Stobaeus
- Stochastic
- Stochastic approximation
- Stochastic basis
- Stochastic Calculus or Stochastic calculus
- Stochastic dependence
- Stochastic differential
- Stochastic differential equation
- Stochastic game
- Stochastic integral
- Stochastic matrix
- Stochastic optimization
- Stochastic process or Stochastic Process
- Stochastic programming
- Stochastic Resonance or Stochastic resonance
- Stoic
- Stokes formula
- Stokes parameters
- Stokes theorem
- Stokes' Theorem or Stokes' theorem
- Stolarsky mean
- Stolz-Cesaro theorem
- Stone space
- Stone-Cech compactification or Stone-cech compactification
- Stone-von Neumann theorem
- Stone-Weierstrass theorem
- Stone-Čech compactification
- Stoneham number
- Stopper knot
- Stopping rule
- Stopping time
- Strabo
- Straight angle
- Straight line
- Straight polyomino
- Straightedge
- Strange Attractor or Strange attractor
- Strange loop
- Strangers
- Strategy
- Strategy (game theory)
- Strategy (in game theory)
- Stratification
- Stratified manifold
- Stratified sample
- Stratified sampling
- Stratonovich integral
- Stream function
- Streamline
- Stress tensor
- Stretch
- Strict
- Strict inequality
- Strict order
- Strictly lower triangular matrix
- Strictly non-palindromic number
- Strictly upper triangular matrix
- String
- String (computer science)
- String figure
- String rewriting
- String rewriting system
- Strip
- Strobogrammatic number
- Strobogrammatic prime
- Strombus
- Strong AI thesis
- Strong convergence
- Strong Frobenius pseudoprime
- Strong Goldbach Conjecture or Strong Goldbach conjecture
- Strong Law of Large Numbers or Strong law of large numbers
- Strong Law of Small Numbers
- Strong Lucas Pseudoprime or Strong Lucas pseudoprime
- Strong mixing
- Strong perfect graph conjecture
- Strong perfect graph theorem
- Strong prime
- Strong pseudoprime
- Strong topology
- Strong Weil curve
- Strongly connected component
- Strongly connected graph
- Strongly regular graph
- Strophoid
- Strouhal number
- Structural linguistics
- Structural stability
- Structurally stable
- Structure
- Structure constant
- Structure factor
- Structure preserving mappings
- Structure sheaf
- Structures
- Strut
- STS
- Student's t-distribution
- Stunted projective space
- Sturm Chain or Sturm chain
- Sturm theorem
- Sturm's theorem or Sturm's Theorem
- Sturm-Liouville equation
- Sturm-Liouville operator
- Sturm-Liouville problem
- Sturm-Liouville theory
- Sturmian Sequence or Sturmian sequence
- SU or Su
- Sub-linear
- Sub-Riemannian manifold
- Subadditive
- Subalgebra
- Subbasis
- Subbundle
- Subcategory
- Subcontrary mean
- Subdifferential
- Subdivision
- Subdivision (graph theory)
- Subfactorial
- Subfield
- Subgraph
- Subgroup
- Subharmonic function
- Sublime number
- Sublinear function
- Submanifold
- Submatrix
- Submersion
- Submodule
- Submonoid
- Subnormal series
- Subnormal subgroup
- Subobject
- Subobject classifier
- Subring
- Subscript
- Subsemigroup
- Subsequence
- Subset
- Subset sum problem
- Subsets
- Subspace
- Subspace topology
- Substantive Derivative or Substantive derivative
- Substitution for integration
- Substitution rule
- Substring
- Substructure
- Subtend
- Subtraction
- Subtrahend
- Subtree
- Subvariety
- Successive Overrelaxation Method or Successive Overrelaxation method or Successive overrelaxation method
- Successor
- Successor cardinal
- Sudoku or SuDoku
- Sufficient
- Sufficient statistic
- Sufficiently large
- Suffix
- Sultan's Dowry Problem or Sultan's dowry problem
- Sum of series
- Sum rule
- Sum-free set
- Sum-product number
- Summand
- Summation
- Summation by parts
- Summation methods
- Sumset
- Sup
- Super-group
- Super-manifold
- Super-Poulet Number or Super-Poulet number
- Super-space
- Superabundant number
- Superadditive
- Superalgebra
- Supercommutative
- Superconvergence
- Superdiagonal
- Superegg
- Superellipse
- Superfactorial
- Superformula
- Supergraph
- Superharmonic function
- Superior highly composite number
- Supernormal
- Superposition principle
- Superscript
- Superset
- Supersingular
- Supersingular elliptic curve
- Supersingular prime
- Supersolvable group
- Superstructure
- Supersymmetry
- Supplementary angle
- Supplementary angles
- Support
- Support function
- Support of a distribution
- Support of a function
- Support of distribution
- Support of function
- Supporting hyperplane
- Supremum
- Supremum limit
- Supremum norm
- Surd
- Surface
- Surface Area or Surface area
- Surface bundle over the circle
- Surface integral
- Surface normal
- Surface of revolution
- Surgery
- Surjection
- Surjective
- Surjective map
- Surprise examination paradox
- Surreal number
- Surreal numbers
- Surrogate
- Survival function
- Survivor function
- Susan Howson
- Suslin hypothesis
- Suslin problem
- Suslin tree
- Suspension
- Suspension (topology)
- Suspension
- Suzuki group
- Suzuki sporadic group
- Swastika
- Swirl
- Swung dash
- Syllogism
- Sylow
- Sylow p-subgroup
- Sylow p-subgroups
- Sylow subgroup
- Sylow theorems
- Sylow's first theorem
- Sylow's third theorem
- Sylvester matrix
- Sylvester's criterion
- Sylvester's law
- Sylvester's sequence
- Sylvester's theorem
- Sylvester-Gallai theorem
- Symbol of an elliptic operator
- Symbolic computation
- Symbolic dynamics
- Symbolic integration
- Symbolic Logic or Symbolic logic
- Symbolic system
- Symmedian
- Symmedian point
- Symmetric
- Symmetric algebra
- Symmetric bilinear form
- Symmetric derivative
- Symmetric design
- Symmetric difference
- Symmetric function
- Symmetric graph
- Symmetric group
- Symmetric matrix
- Symmetric operator
- Symmetric polynomial
- Symmetric relation
- Symmetric space
- Symmetric tensor or Symmetric Tensor
- Symmetrization
- Symmetry
- Symmetry group
- Symmetry operation
- Symplectic form
- Symplectic Geometry or Symplectic geometry
- Symplectic group
- Symplectic manifold
- Symplectic matrix
- Symplectic quotient
- Symplectic space
- Symplectic structure
- Symplectic vector field
- Symplectic vector space
- Symplectomorphism
- Synergetics
- Synodic month
- Syntactic structure
- Syntax
- Synthetic differential geometry
- Synthetic division or Synthetic Division
- Syracuse problem
- Syrianus
- System identification
- System of distinct representatives
- System of equations
- System of linear equations
- System programming
- System state
- Systematic sampling
- Syzygy
- Szekeres snark
- Szemeredi's theorem
- Szemerédi's regularity lemma
- Szemerédi's theorem
- Szemerédi-Trotter theorem
- Szilassi Polyhedron or Szilassi polyhedron
