- Uban Number ({{MathWorld | urlname=UbanNumber | title=Uban Number}}): Uban Number
- Ubiquitous Constant ({{MathWorld | urlname=UbiquitousConstant | title=Ubiquitous Constant}}): Ubiquitous Constant
- Ulam Map ({{MathWorld | urlname=UlamMap | title=Ulam Map}}): Ulam Map
- Ulam Number ({{MathWorld | urlname=UlamNumber | title=Ulam Number}}): Ulam Number
- Ulam's Conjecture ({{MathWorld | urlname=UlamsConjecture | title=Ulam's Conjecture}}): Ulam's Conjecture
- Ulam Sequence ({{MathWorld | urlname=UlamSequence | title=Ulam Sequence}}): Ulam Sequence
- Ulam's Problem ({{MathWorld | urlname=UlamsProblem | title=Ulam's Problem}}): Ulam's Problem
- Ulam's Spiral ({{MathWorld | urlname=UlamsSpiral | title=Ulam's Spiral}}): Ulam's Spiral
- Ultimate Question Graph ({{MathWorld | urlname=UltimateQuestionGraph | title=Ultimate Question Graph}}): Ultimate Question Graph
- Ultradistribution ({{MathWorld | urlname=Ultradistribution | title=Ultradistribution}}): Ultradistribution
- Ultrafactorial ({{MathWorld | urlname=Ultrafactorial | title=Ultrafactorial}}): Ultrafactorial
- Ultrafilter ({{MathWorld | urlname=Ultrafilter | title=Ultrafilter}}): Ultrafilter
- Ultrametric ({{MathWorld | urlname=Ultrametric | title=Ultrametric}}): Ultrametric
- Ultrapower ({{MathWorld | urlname=Ultrapower | title=Ultrapower}}): Ultrapower
- Ultraproduct ({{MathWorld | urlname=Ultraproduct | title=Ultraproduct}}): Ultraproduct
- Ultraradical ({{MathWorld | urlname=Ultraradical | title=Ultraradical}}): Ultraradical
- Ultraspherical Differe... ({{MathWorld | urlname=UltrasphericalDifferentialEquation | title=Ultraspherical Differe...}}): Ultraspherical Differe...
- Ultraspherical Function ({{MathWorld | urlname=UltrasphericalFunction | title=Ultraspherical Function}}): Ultraspherical Function
- Ultraspherical Polynomial ({{MathWorld | urlname=UltrasphericalPolynomial | title=Ultraspherical Polynomial}}): Ultraspherical Polynomial
- Umbilic Point ({{MathWorld | urlname=UmbilicPoint | title=Umbilic Point}}): Umbilic Point
- Umbral Algebra ({{MathWorld | urlname=UmbralAlgebra | title=Umbral Algebra}}): Umbral Algebra
- Umbral Calculus ({{MathWorld | urlname=UmbralCalculus | title=Umbral Calculus}}): Umbral Calculus
- Umbral Operator ({{MathWorld | urlname=UmbralOperator | title=Umbral Operator}}): Umbral Operator
- Umbrella ({{MathWorld | urlname=Umbrella | title=Umbrella}}): Umbrella
- Umbrella Graph ({{MathWorld | urlname=UmbrellaGraph | title=Umbrella Graph}}): Umbrella Graph
- Unambiguous ({{MathWorld | urlname=Unambiguous | title=Unambiguous}}): Unambiguous
- Unar ({{MathWorld | urlname=Unar | title=Unar}}): Unar
- Unary Cofactor Triangle ({{MathWorld | urlname=UnaryCofactorTriangle | title=Unary Cofactor Triangle}}): Unary Cofactor Triangle
- Unary Operation ({{MathWorld | urlname=UnaryOperation | title=Unary Operation}}): Unary Operation
- U(n) Basic Hypergeomet... ({{MathWorld | urlname=UnBasicHypergeometricSeries | title=U(n) Basic Hypergeomet...}}): U(n) Basic Hypergeomet...
- Unbiased Estimator ({{MathWorld | urlname=UnbiasedEstimator | title=Unbiased Estimator}}): Unbiased Estimator
- Unbounded ({{MathWorld | urlname=Unbounded | title=Unbounded}}): Unbounded
- Uncia ({{MathWorld | urlname=Uncia | title=Uncia}}): Uncia
- Unconstrained Optimiza... ({{MathWorld | urlname=UnconstrainedOptimization | title=Unconstrained Optimiza...}}): Unconstrained Optimiza...
- Uncorrelated ({{MathWorld | urlname=Uncorrelated | title=Uncorrelated}}): Uncorrelated
- Uncorrelated Numbers ({{MathWorld | urlname=UncorrelatedNumbers | title=Uncorrelated Numbers}}): Uncorrelated Numbers
- Uncountable Set ({{MathWorld | urlname=UncountableSet | title=Uncountable Set}}): Uncountable Set
- Uncountably Infinite ({{MathWorld | urlname=UncountablyInfinite | title=Uncountably Infinite}}): Uncountably Infinite
- Undecagon ({{MathWorld | urlname=Undecagon | title=Undecagon}}): Undecagon
- Undecahedron ({{MathWorld | urlname=Undecahedron | title=Undecahedron}}): Undecahedron
- Undecidable ({{MathWorld | urlname=Undecidable | title=Undecidable}}): Undecidable
- Undecillion ({{MathWorld | urlname=Undecillion | title=Undecillion}}): Undecillion
- Undefined ({{MathWorld | urlname=Undefined | title=Undefined}}): Undefined
- Underbar ({{MathWorld | urlname=Underbar | title=Underbar}}): Underbar
- Underbrace ({{MathWorld | urlname=Underbrace | title=Underbrace}}): Underbrace
- Underdamping ({{MathWorld | urlname=Underdamping | title=Underdamping}}): Underdamping
- Underdot ({{MathWorld | urlname=Underdot | title=Underdot}}): Underdot
- Underlying Functor ({{MathWorld | urlname=UnderlyingFunctor | title=Underlying Functor}}): Underlying Functor
- Underlying Space ({{MathWorld | urlname=UnderlyingSpace | title=Underlying Space}}): Underlying Space
- Underscore ({{MathWorld | urlname=Underscore | title=Underscore}}): Underscore
- Undetermined Coefficie... ({{MathWorld | urlname=UndeterminedCoefficientsMethod | title=Undetermined Coefficie...}}): Undetermined Coefficie...
- Undirected Graph ({{MathWorld | urlname=UndirectedGraph | title=Undirected Graph}}): Undirected Graph
- Undulating Number ({{MathWorld | urlname=UndulatingNumber | title=Undulating Number}}): Undulating Number
- Unduloid ({{MathWorld | urlname=Unduloid | title=Unduloid}}): Unduloid
- Unequal ({{MathWorld | urlname=Unequal | title=Unequal}}): Unequal
- Unexpected Hanging Par... ({{MathWorld | urlname=UnexpectedHangingParadox | title=Unexpected Hanging Par...}}): Unexpected Hanging Par...
- Unfair Game ({{MathWorld | urlname=UnfairGame | title=Unfair Game}}): Unfair Game
- Unfinished Game ({{MathWorld | urlname=UnfinishedGame | title=Unfinished Game}}): Unfinished Game
- Unfolding ({{MathWorld | urlname=Unfolding | title=Unfolding}}): Unfolding
- Unhappy Number ({{MathWorld | urlname=UnhappyNumber | title=Unhappy Number}}): Unhappy Number
- Unicity Theorem ({{MathWorld | urlname=UnicityTheorem | title=Unicity Theorem}}): Unicity Theorem
- Unicoherent Space ({{MathWorld | urlname=UnicoherentSpace | title=Unicoherent Space}}): Unicoherent Space
- Unicursal Circuit ({{MathWorld | urlname=UnicursalCircuit | title=Unicursal Circuit}}): Unicursal Circuit
- Unicyclic Graph ({{MathWorld | urlname=UnicyclicGraph | title=Unicyclic Graph}}): Unicyclic Graph
- Unidecagon ({{MathWorld | urlname=Unidecagon | title=Unidecagon}}): Unidecagon
- Unifiable ({{MathWorld | urlname=Unifiable | title=Unifiable}}): Unifiable
- Unification ({{MathWorld | urlname=Unification | title=Unification}}): Unification
- Unifier ({{MathWorld | urlname=Unifier | title=Unifier}}): Unifier
- Uniform Apodization Fu... ({{MathWorld | urlname=UniformApodizationFunction | title=Uniform Apodization Fu...}}): Uniform Apodization Fu...
- Uniform Boundedness Pr... ({{MathWorld | urlname=UniformBoundednessPrinciple | title=Uniform Boundedness Pr...}}): Uniform Boundedness Pr...
- Uniform Circular Motion ({{MathWorld | urlname=UniformCircularMotion | title=Uniform Circular Motion}}): Uniform Circular Motion
- Uniform Convergence ({{MathWorld | urlname=UniformConvergence | title=Uniform Convergence}}): Uniform Convergence
- Uniform Convexity ({{MathWorld | urlname=UniformConvexity | title=Uniform Convexity}}): Uniform Convexity
- Uniform Difference Dis... ({{MathWorld | urlname=UniformDifferenceDistribution | title=Uniform Difference Dis...}}): Uniform Difference Dis...
- Uniform Distribution ({{MathWorld | urlname=UniformDistribution | title=Uniform Distribution}}): Uniform Distribution
- Uniform Distribution T... ({{MathWorld | urlname=UniformDistributionTheory | title=Uniform Distribution T...}}): Uniform Distribution T...
- Uniform Great Rhombico... ({{MathWorld | urlname=UniformGreatRhombicosidodecahedron | title=Uniform Great Rhombico...}}): Uniform Great Rhombico...
- Uniform Great Rhombicu... ({{MathWorld | urlname=UniformGreatRhombicuboctahedron | title=Uniform Great Rhombicu...}}): Uniform Great Rhombicu...
- Uniformity Conjecture ({{MathWorld | urlname=UniformityConjecture | title=Uniformity Conjecture}}): Uniformity Conjecture
- Uniformization ({{MathWorld | urlname=Uniformization | title=Uniformization}}): Uniformization
- Uniformization Theorem ({{MathWorld | urlname=UniformizationTheorem | title=Uniformization Theorem}}): Uniformization Theorem
- Uniformly Cauchy ({{MathWorld | urlname=UniformlyCauchy | title=Uniformly Cauchy}}): Uniformly Cauchy
- Uniformly Distributed... ({{MathWorld | urlname=UniformlyDistributedSequence | title=Uniformly Distributed...}}): Uniformly Distributed...
- Uniform Polychoron ({{MathWorld | urlname=UniformPolychoron | title=Uniform Polychoron}}): Uniform Polychoron
- Uniform Polyhedron ({{MathWorld | urlname=UniformPolyhedron | title=Uniform Polyhedron}}): Uniform Polyhedron
- Uniform Product Distri... ({{MathWorld | urlname=UniformProductDistribution | title=Uniform Product Distri...}}): Uniform Product Distri...
- Uniform Ratio Distribu... ({{MathWorld | urlname=UniformRatioDistribution | title=Uniform Ratio Distribu...}}): Uniform Ratio Distribu...
- Uniform Sum Distribution ({{MathWorld | urlname=UniformSumDistribution | title=Uniform Sum Distribution}}): Uniform Sum Distribution
- Uniform Tessellation ({{MathWorld | urlname=UniformTessellation | title=Uniform Tessellation}}): Uniform Tessellation
- Uniform Variate ({{MathWorld | urlname=UniformVariate | title=Uniform Variate}}): Uniform Variate
- Unilateral Laplace Tra... ({{MathWorld | urlname=UnilateralLaplaceTransform | title=Unilateral Laplace Tra...}}): Unilateral Laplace Tra...
- Unilateral Shift ({{MathWorld | urlname=UnilateralShift | title=Unilateral Shift}}): Unilateral Shift
- Unilateral Z-Transform ({{MathWorld | urlname=UnilateralZ-Transform | title=Unilateral Z-Transform}}): Unilateral Z-Transform
- Unimodal ({{MathWorld | urlname=Unimodal | title=Unimodal}}): Unimodal
- Unimodal Distribution ({{MathWorld | urlname=UnimodalDistribution | title=Unimodal Distribution}}): Unimodal Distribution
- Unimodal Polynomial ({{MathWorld | urlname=UnimodalPolynomial | title=Unimodal Polynomial}}): Unimodal Polynomial
- Unimodal Sequence ({{MathWorld | urlname=UnimodalSequence | title=Unimodal Sequence}}): Unimodal Sequence
- Unimodular Group ({{MathWorld | urlname=UnimodularGroup | title=Unimodular Group}}): Unimodular Group
- Unimodular Matrix ({{MathWorld | urlname=UnimodularMatrix | title=Unimodular Matrix}}): Unimodular Matrix
- Unimodular Transformation ({{MathWorld | urlname=UnimodularTransformation | title=Unimodular Transformation}}): Unimodular Transformation
- Union ({{MathWorld | urlname=Union | title=Union}}): Union
- Union-Closed Set ({{MathWorld | urlname=Union-ClosedSet | title=Union-Closed Set}}): Union-Closed Set
- Union-Closed Sets Conj... ({{MathWorld | urlname=Union-ClosedSetsConjecture | title=Union-Closed Sets Conj...}}): Union-Closed Sets Conj...
- Uniplanar Double Point ({{MathWorld | urlname=UniplanarDoublePoint | title=Uniplanar Double Point}}): Uniplanar Double Point
- Unipotent ({{MathWorld | urlname=Unipotent | title=Unipotent}}): Unipotent
- Unique ({{MathWorld | urlname=Unique | title=Unique}}): Unique
- Unique Factorization ({{MathWorld | urlname=UniqueFactorization | title=Unique Factorization}}): Unique Factorization
- Unique Factorization D... ({{MathWorld | urlname=UniqueFactorizationDomain | title=Unique Factorization D...}}): Unique Factorization D...
- Unique Factorization T... ({{MathWorld | urlname=UniqueFactorizationTheorem | title=Unique Factorization T...}}): Unique Factorization T...
- Uniquely Complemented... ({{MathWorld | urlname=UniquelyComplementedLattice | title=Uniquely Complemented...}}): Uniquely Complemented...
- Uniquely k-Colorable G... ({{MathWorld | urlname=Uniquelyk-ColorableGraph | title=Uniquely k-Colorable G...}}): Uniquely k-Colorable G...
- Uniqueness Theorem ({{MathWorld | urlname=UniquenessTheorem | title=Uniqueness Theorem}}): Uniqueness Theorem
- Unique Prime ({{MathWorld | urlname=UniquePrime | title=Unique Prime}}): Unique Prime
- Unistable Polyhedron ({{MathWorld | urlname=UnistablePolyhedron | title=Unistable Polyhedron}}): Unistable Polyhedron
- Unit ({{MathWorld | urlname=Unit | title=Unit}}): Unit
- Unital ({{MathWorld | urlname=Unital | title=Unital}}): Unital
- Unitarily Equivalent ({{MathWorld | urlname=UnitarilyEquivalent | title=Unitarily Equivalent}}): Unitarily Equivalent
- Unitary ({{MathWorld | urlname=Unitary | title=Unitary}}): Unitary
- Unitary Aliquot Sequence ({{MathWorld | urlname=UnitaryAliquotSequence | title=Unitary Aliquot Sequence}}): Unitary Aliquot Sequence
- Unitary Amicable Pair ({{MathWorld | urlname=UnitaryAmicablePair | title=Unitary Amicable Pair}}): Unitary Amicable Pair
- Unitary Basis ({{MathWorld | urlname=UnitaryBasis | title=Unitary Basis}}): Unitary Basis
- Unitary Divisor ({{MathWorld | urlname=UnitaryDivisor | title=Unitary Divisor}}): Unitary Divisor
- Unitary Divisor Function ({{MathWorld | urlname=UnitaryDivisorFunction | title=Unitary Divisor Function}}): Unitary Divisor Function
- Unitary Element ({{MathWorld | urlname=UnitaryElement | title=Unitary Element}}): Unitary Element
- Unitary Group ({{MathWorld | urlname=UnitaryGroup | title=Unitary Group}}): Unitary Group
- Unitary Matrix ({{MathWorld | urlname=UnitaryMatrix | title=Unitary Matrix}}): Unitary Matrix
- Unitary Multiperfect N... ({{MathWorld | urlname=UnitaryMultiperfectNumber | title=Unitary Multiperfect N...}}): Unitary Multiperfect N...
- Unitary Multiplicative... ({{MathWorld | urlname=UnitaryMultiplicativeCharacter | title=Unitary Multiplicative...}}): Unitary Multiplicative...
- Unitary Perfect Number ({{MathWorld | urlname=UnitaryPerfectNumber | title=Unitary Perfect Number}}): Unitary Perfect Number
- Unitary Representation ({{MathWorld | urlname=UnitaryRepresentation | title=Unitary Representation}}): Unitary Representation
- Unitary Sociable Numbers ({{MathWorld | urlname=UnitarySociableNumbers | title=Unitary Sociable Numbers}}): Unitary Sociable Numbers
- Unitary Transformation ({{MathWorld | urlname=UnitaryTransformation | title=Unitary Transformation}}): Unitary Transformation
- Unitary Unimodular Group ({{MathWorld | urlname=UnitaryUnimodularGroup | title=Unitary Unimodular Group}}): Unitary Unimodular Group
- Unit Ball ({{MathWorld | urlname=UnitBall | title=Unit Ball}}): Unit Ball
- Unit Box ({{MathWorld | urlname=UnitBox | title=Unit Box}}): Unit Box
- Unit Cell ({{MathWorld | urlname=UnitCell | title=Unit Cell}}): Unit Cell
- Unit Circle ({{MathWorld | urlname=UnitCircle | title=Unit Circle}}): Unit Circle
- Unit Cube ({{MathWorld | urlname=UnitCube | title=Unit Cube}}): Unit Cube
- Unit Disk ({{MathWorld | urlname=UnitDisk | title=Unit Disk}}): Unit Disk
- Unit Disk Integral ({{MathWorld | urlname=UnitDiskIntegral | title=Unit Disk Integral}}): Unit Disk Integral
- Unit-Distance Graph ({{MathWorld | urlname=Unit-DistanceGraph | title=Unit-Distance Graph}}): Unit-Distance Graph
- Unit Element ({{MathWorld | urlname=UnitElement | title=Unit Element}}): Unit Element
- Unit Fraction ({{MathWorld | urlname=UnitFraction | title=Unit Fraction}}): Unit Fraction
- Unit Interval ({{MathWorld | urlname=UnitInterval | title=Unit Interval}}): Unit Interval
- Unitization ({{MathWorld | urlname=Unitization | title=Unitization}}): Unitization
- Unit Lattice ({{MathWorld | urlname=UnitLattice | title=Unit Lattice}}): Unit Lattice
- Unit Matrix ({{MathWorld | urlname=UnitMatrix | title=Unit Matrix}}): Unit Matrix
- Unit Neighborhood Graph ({{MathWorld | urlname=UnitNeighborhoodGraph | title=Unit Neighborhood Graph}}): Unit Neighborhood Graph
- Unit Normal ({{MathWorld | urlname=UnitNormal | title=Unit Normal}}): Unit Normal
- Unit Point ({{MathWorld | urlname=UnitPoint | title=Unit Point}}): Unit Point
- Unitransitive Graph ({{MathWorld | urlname=UnitransitiveGraph | title=Unitransitive Graph}}): Unitransitive Graph
- Unit Ring ({{MathWorld | urlname=UnitRing | title=Unit Ring}}): Unit Ring
- Unit Sphere ({{MathWorld | urlname=UnitSphere | title=Unit Sphere}}): Unit Sphere
- Unit Square ({{MathWorld | urlname=UnitSquare | title=Unit Square}}): Unit Square
- Unit Square Integral ({{MathWorld | urlname=UnitSquareIntegral | title=Unit Square Integral}}): Unit Square Integral
- Unit Step ({{MathWorld | urlname=UnitStep | title=Unit Step}}): Unit Step
- Unit Step Function ({{MathWorld | urlname=UnitStepFunction | title=Unit Step Function}}): Unit Step Function
- Unit Triangle ({{MathWorld | urlname=UnitTriangle | title=Unit Triangle}}): Unit Triangle
- Unit Vector ({{MathWorld | urlname=UnitVector | title=Unit Vector}}): Unit Vector
- Unity ({{MathWorld | urlname=Unity | title=Unity}}): Unity
- Univalent ({{MathWorld | urlname=Univalent | title=Univalent}}): Univalent
- Univalent Function ({{MathWorld | urlname=UnivalentFunction | title=Univalent Function}}): Univalent Function
- Univariate ({{MathWorld | urlname=Univariate | title=Univariate}}): Univariate
- Univariate Function ({{MathWorld | urlname=UnivariateFunction | title=Univariate Function}}): Univariate Function
- Univariate Polynomial ({{MathWorld | urlname=UnivariatePolynomial | title=Univariate Polynomial}}): Univariate Polynomial
- Universal Algebra ({{MathWorld | urlname=UniversalAlgebra | title=Universal Algebra}}): Universal Algebra
- Universal Bound ({{MathWorld | urlname=UniversalBound | title=Universal Bound}}): Universal Bound
- Universal Category ({{MathWorld | urlname=UniversalCategory | title=Universal Category}}): Universal Category
- Universal Cellular Aut... ({{MathWorld | urlname=UniversalCellularAutomaton | title=Universal Cellular Aut...}}): Universal Cellular Aut...
- Universal Cover ({{MathWorld | urlname=UniversalCover | title=Universal Cover}}): Universal Cover
- Universal Differential... ({{MathWorld | urlname=UniversalDifferentialEquation | title=Universal Differential...}}): Universal Differential...
- Universal Form ({{MathWorld | urlname=UniversalForm | title=Universal Form}}): Universal Form
- Universal Formula ({{MathWorld | urlname=UniversalFormula | title=Universal Formula}}): Universal Formula
- Universal Graph ({{MathWorld | urlname=UniversalGraph | title=Universal Graph}}): Universal Graph
- Universal Hash Function ({{MathWorld | urlname=UniversalHashFunction | title=Universal Hash Function}}): Universal Hash Function
- Universality ({{MathWorld | urlname=Universality | title=Universality}}): Universality
- Universality Class ({{MathWorld | urlname=UniversalityClass | title=Universality Class}}): Universality Class
- Universal Metric Space ({{MathWorld | urlname=UniversalMetricSpace | title=Universal Metric Space}}): Universal Metric Space
- Universal Parabolic Co... ({{MathWorld | urlname=UniversalParabolicConstant | title=Universal Parabolic Co...}}): Universal Parabolic Co...
- Universal Predicate ({{MathWorld | urlname=UniversalPredicate | title=Universal Predicate}}): Universal Predicate
- Universal Product Code ({{MathWorld | urlname=UniversalProductCode | title=Universal Product Code}}): Universal Product Code
- Universal Property ({{MathWorld | urlname=UniversalProperty | title=Universal Property}}): Universal Property
- Universal Quantifier ({{MathWorld | urlname=UniversalQuantifier | title=Universal Quantifier}}): Universal Quantifier
- Universal Quantor ({{MathWorld | urlname=UniversalQuantor | title=Universal Quantor}}): Universal Quantor
- Universal Sentence ({{MathWorld | urlname=UniversalSentence | title=Universal Sentence}}): Universal Sentence
- Universal Set ({{MathWorld | urlname=UniversalSet | title=Universal Set}}): Universal Set
- Universal Space ({{MathWorld | urlname=UniversalSpace | title=Universal Space}}): Universal Space
- Universal Turing Machine ({{MathWorld | urlname=UniversalTuringMachine | title=Universal Turing Machine}}): Universal Turing Machine
- Universal Vassiliev In... ({{MathWorld | urlname=UniversalVassilievInvariant | title=Universal Vassiliev In...}}): Universal Vassiliev In...
- Universe ({{MathWorld | urlname=Universe | title=Universe}}): Universe
- Unknot ({{MathWorld | urlname=Unknot | title=Unknot}}): Unknot
- Unknotting Number ({{MathWorld | urlname=UnknottingNumber | title=Unknotting Number}}): Unknotting Number
- Unknown ({{MathWorld | urlname=Unknown | title=Unknown}}): Unknown
- Unlabeled Graph ({{MathWorld | urlname=UnlabeledGraph | title=Unlabeled Graph}}): Unlabeled Graph
- Unless ({{MathWorld | urlname=Unless | title=Unless}}): Unless
- Unlesss ({{MathWorld | urlname=Unlesss | title=Unlesss}}): Unlesss
- Unlink ({{MathWorld | urlname=Unlink | title=Unlink}}): Unlink
- Unmixed ({{MathWorld | urlname=Unmixed | title=Unmixed}}): Unmixed
- Unordered Factorization ({{MathWorld | urlname=UnorderedFactorization | title=Unordered Factorization}}): Unordered Factorization
- Unpoke Move ({{MathWorld | urlname=UnpokeMove | title=Unpoke Move}}): Unpoke Move
- Unprojected Map ({{MathWorld | urlname=UnprojectedMap | title=Unprojected Map}}): Unprojected Map
- Unrestricted Partition... ({{MathWorld | urlname=UnrestrictedPartitionFunctionP | title=Unrestricted Partition...}}): Unrestricted Partition...
- Unrooted Tree ({{MathWorld | urlname=UnrootedTree | title=Unrooted Tree}}): Unrooted Tree
- Unsafe ({{MathWorld | urlname=Unsafe | title=Unsafe}}): Unsafe
- Unsatisfiable ({{MathWorld | urlname=Unsatisfiable | title=Unsatisfiable}}): Unsatisfiable
- Unsolved Problems ({{MathWorld | urlname=UnsolvedProblems | title=Unsolved Problems}}): Unsolved Problems
- Unsorted Union ({{MathWorld | urlname=UnsortedUnion | title=Unsorted Union}}): Unsorted Union
- Unstable Improper Node ({{MathWorld | urlname=UnstableImproperNode | title=Unstable Improper Node}}): Unstable Improper Node
- Unstable Node ({{MathWorld | urlname=UnstableNode | title=Unstable Node}}): Unstable Node
- Unstable Spiral Point ({{MathWorld | urlname=UnstableSpiralPoint | title=Unstable Spiral Point}}): Unstable Spiral Point
- Unstable Star ({{MathWorld | urlname=UnstableStar | title=Unstable Star}}): Unstable Star
- Untouchable Number ({{MathWorld | urlname=UntouchableNumber | title=Untouchable Number}}): Untouchable Number
- U-Number ({{MathWorld | urlname=U-Number | title=U-Number}}): U-Number
- Unusual Number ({{MathWorld | urlname=UnusualNumber | title=Unusual Number}}): Unusual Number
- UPC ({{MathWorld | urlname=UPC | title=UPC}}): UPC
- Upper Bound ({{MathWorld | urlname=UpperBound | title=Upper Bound}}): Upper Bound
- Upper Half-Disk ({{MathWorld | urlname=UpperHalf-Disk | title=Upper Half-Disk}}): Upper Half-Disk
- Upper Half-Plane ({{MathWorld | urlname=UpperHalf-Plane | title=Upper Half-Plane}}): Upper Half-Plane
- Upper Integral ({{MathWorld | urlname=UpperIntegral | title=Upper Integral}}): Upper Integral
- Upper Limit ({{MathWorld | urlname=UpperLimit | title=Upper Limit}}): Upper Limit
- Upper Lip Continuity ({{MathWorld | urlname=UpperLipContinuity | title=Upper Lip Continuity}}): Upper Lip Continuity
- Upper Sum ({{MathWorld | urlname=UpperSum | title=Upper Sum}}): Upper Sum
- Upper Triangular Matrix ({{MathWorld | urlname=UpperTriangularMatrix | title=Upper Triangular Matrix}}): Upper Triangular Matrix
- Upper-Trimmed Subsequence ({{MathWorld | urlname=Upper-TrimmedSubsequence | title=Upper-Trimmed Subsequence}}): Upper-Trimmed Subsequence
- Uppuluri-Carpenter Number ({{MathWorld | urlname=Uppuluri-CarpenterNumber | title=Uppuluri-Carpenter Number}}): Uppuluri-Carpenter Number
- Upward Drawing ({{MathWorld | urlname=UpwardDrawing | title=Upward Drawing}}): Upward Drawing
- Urchin ({{MathWorld | urlname=Urchin | title=Urchin}}): Urchin
- Urelement ({{MathWorld | urlname=Urelement | title=Urelement}}): Urelement
- Urn Problem ({{MathWorld | urlname=UrnProblem | title=Urn Problem}}): Urn Problem
- Urquhart's Theorem ({{MathWorld | urlname=UrquhartsTheorem | title=Urquhart's Theorem}}): Urquhart's Theorem
- Urysohn Function ({{MathWorld | urlname=UrysohnFunction | title=Urysohn Function}}): Urysohn Function
- Urysohn's Lemma ({{MathWorld | urlname=UrysohnsLemma | title=Urysohn's Lemma}}): Urysohn's Lemma
- Urysohn's Metrization... ({{MathWorld | urlname=UrysohnsMetrizationTheorem | title=Urysohn's Metrization...}}): Urysohn's Metrization...
- U-Statistic ({{MathWorld | urlname=U-Statistic | title=U-Statistic}}): U-Statistic
- Usual Topology ({{MathWorld | urlname=UsualTopology | title=Usual Topology}}): Usual Topology
- Utility Graph ({{MathWorld | urlname=UtilityGraph | title=Utility Graph}}): Utility Graph
- Utility Problem ({{MathWorld | urlname=UtilityProblem | title=Utility Problem}}): Utility Problem
