- H-cobordism or H-Cobordism
- H-cobordism theorem
- H-Fractal or H-fractal
- H-Function
- H-principle
- H-space
- Haag theorem
- Haar function
- Haar integral or Haar Integral
- Haar measure
- Habilitation
- Hackenbush
- Hadamard factorization theorem
- Hadamard gap theorem
- Hadamard matrix
- Hadamard product
- Hadamard three-circle theorem
- Hadamard transform
- Hadamard's inequality
- Hadwiger number
- Hadwiger-Finsler inequality or Hadwiger-finsler inequality
- Hafner-Sarnak-McCurley constant
- Hahn decomposition
- Hahn decomposition theorem
- Hahn-Banach theorem
- Hahn-Kolmogorov theorem
- Hahn-Mazurkiewicz theorem
- Hailstone number
- Hairy ball theorem
- Haken manifold
- Hales-Jewett theorem
- Half
- Half form
- Half-angle formulas
- Half-closed interval
- Half-line
- Half-line (ray)
- Half-open interval
- Half-period ratio
- Half-plane
- Half-Space or Half-space
- Hall polynomial
- Hall set
- Hall subgroup
- Hall's theorem
- Hall-Janko graph
- Hall-Janko group
- Halley's method
- Halting problem or Halting Problem
- Halton sequence
- Ham sandwich theorem
- Ham-sandwich theorem
- Hamburger moment problem
- Hamel basis
- Hamilton circuit
- Hamilton cycle
- Hamilton equations
- Hamilton graph
- Hamilton group
- Hamilton path
- Hamilton's equations or Hamilton's Equations
- Hamilton's rules
- Hamilton-connected graph
- Hamilton-Jacobi theory
- Hamiltonian
- Hamiltonian circuit
- Hamiltonian Cycle or Hamiltonian cycle
- Hamiltonian graph
- Hamiltonian group
- Hamiltonian path
- Hamiltonian quaternions
- Hamiltonian System or Hamiltonian system
- Hamiltonian vector field
- Hammer projection
- Hamming Code or Hamming code
- Hamming distance or Hamming Distance
- Hamming function
- Hamming graph
- Hamming metric
- Hamming window
- Handedness
- Handle
- Handle decomposition
- Handlebody
- Handshake problem
- Hankel contour
- Hankel function
- Hankel function of the first kind
- Hankel function of the second kind
- Hankel functions
- Hankel matrix
- Hankel operator
- Hankel transform
- Hann function
- Hann window
- Hanna Neumann
- Hanning function
- Hanning window
- Hanoi towers
- Hans Reiter
- Happy end problem
- Happy ending problem or Happy Ending problem
- Happy number or Happy Number
- Harada-Norton group
- Hard core predicate
- Hard Lefschetz theorem
- Hardy function
- Hardy inequality
- Hardy space
- Hardy spaces
- Hardy theorem
- Hardy's inequality
- Hardy's theorem
- Hardy-Littlewood
- Hardy-Littlewood conjectures
- Hardy-Littlewood constant
- Hardy-Littlewood constants
- Hardy-Ramanujan number
- Hardy-Weinberg law
- Harmonic
- Harmonic analysis
- Harmonic conjugate
- Harmonic conjugate function
- Harmonic coordinates
- Harmonic divisor number
- Harmonic equation
- Harmonic form
- Harmonic function
- Harmonic map
- Harmonic mapping
- Harmonic mean or Harmonic Mean
- Harmonic measure
- Harmonic number or Harmonic Number
- Harmonic oscillator or Harmonic Oscillator
- Harmonic polynomial
- Harmonic progression
- Harmonic Series or Harmonic series
- Harmonic spinor
- Harmonic-geometric mean
- Harmonics
- Harmonograph
- Harnack inequality
- Harnack theorem
- Harnack's inequality
- Harnack's principle
- Harnack's theorems
- Harry Dym equation
- Harshad number
- Hartley function
- Hartley Transform or Hartley transform
- Hartman-Grobman theorem
- Hartogs domain
- Hartogs theorem
- Hartogs' lemma
- Hash Function or Hash function
- Hash Table or Hash table
- Hashing
- Haskell
- Hasse diagram or Hasse Diagram
- Hasse invariant
- Hasse principle
- Hasse-Minkowski theorem
- Hat
- Hausdorff
- Hausdorff axiom
- Hausdorff axioms
- Hausdorff dimension
- Hausdorff distance
- Hausdorff maximality theorem
- Hausdorff measure
- Hausdorff metric
- Hausdorff moment problem
- Hausdorff paradox or Hausdorff Paradox
- Hausdorff space
- Hausdorff topology
- Hausdorff-Besicovitch dimension
- Haversine
- Hawaiian earring
- Hawk
- Hazard function
- Hazard rate
- Head
- Heap
- Heaps' law
- Heapsort
- Heat Conduction Equation
- Heat equation
- Heath-Brown-Moroz constant
- Heaviside step function
- Heawood conjecture
- Heawood graph
- Heawood number
- Hebesphenomegacorona
- Hecatonicosachoron
- Hecke algebra
- Hecke character
- Hecke L-function
- Hecke L-Series or Hecke L-series
- Hecke operator
- Hectogon
- Hedetniemi conjecture
- Hedgehog
- Hedgehog metric
- Hedgehog space
- Heegaard decomposition
- Heegaard splitting
- Heegner number
- Heegner point
- Heegner points
- Heesch number
- Heesch's problem
- Height
- Height function
- Height of a polynomial
- Height of a prime ideal
- Height of an ideal
- Height-balanced tree
- Heilbronn triangle problem
- Heine-Borel theorem or Heine-Borel Theorem
- Heine-Cantor theorem
- Heisenberg algebra
- Heisenberg group
- Held group
- Helicoid
- Heliocentric theory
- Helix
- Helly theorem
- Helly's theorem
- Helly-Bray theorem
- Helmholtz differential equation
- Helmholtz equation or Helmholtz Equation
- Helmholtz's Theorem or Helmholtz's theorem
- Hemimetric
- Hemisphere
- Hempel's Paradox or Hempel's paradox
- Hendecagon
- Henri Lebesgue or Henri lebesgue
- Henri Poincaré or Henri poincaré
- Henry VIII Prime or Henry viii prime
- Hensel lemma
- Hensel's lemma
- Henstock-Kurzweil Integral or Henstock-Kurzweil integral
- Heptadecagon
- Heptagon
- Heptagonal number
- Heptagonal pyramidal number
- Heptagram
- Heptahedron
- Heptakaidecagon
- Heptiamond
- Heptomino
- Heracleitus
- Herbrand base
- Herbrand structure
- Herbrand Universe or Herbrand universe
- Herbrand's theorem or Herbrand's Theorem
- Hereditary ring
- Heredity
- Hering illusion
- Hermann grid illusion
- Hermann Weyl character formula
- Hermit Point or Hermit point
- Hermite function
- Hermite identity
- Hermite interpolation
- Hermite interpolation formula
- Hermite normal form
- Hermite Polynomial or Hermite polynomial
- Hermite polynomials
- Hermitian conjugate
- Hermitian form
- Hermitian matrix
- Hermitian metric
- Hermitian operator
- Hermitian structure
- Hermitian symmetric space
- Hermitian Transpose or Hermitian transpose
- Hero's Formula or Hero's formula
- Herodotus
- Heron formula
- Heron triangle
- Heron's formula or Heron's Formula
- Heronian mean
- Heronian tetrahedron
- Heronian triangle
- Herschel
- Herta Freitag
- Hessenberg matrix
- Hessian
- Hessian matrix
- Hessian of a function
- Heteroclinic
- Heteromecic number
- Heteroscedastic
- Heterosquare
- Heun's equation
- Heuristic
- Hex
- Hex game
- Hex number
- Hexa
- Hexabolo
- Hexacontagon
- Hexacosichoron
- Hexadecachoron
- Hexadecagon
- Hexadecimal
- Hexaflexagon
- Hexagon
- Hexagon tiling
- Hexagonal close packing
- Hexagonal dipyramid
- Hexagonal grid
- Hexagonal number
- Hexagonal Prism or Hexagonal prism
- Hexagonal pyramidal number
- Hexagram
- Hexagrammum Mysticum Theorem or Hexagrammum Mysticum theorem or Hexagrammum mysticum theorem
- Hexahedron
- Hexakaidecagon
- Hexakis icosahedron
- Hexakis octahedron
- Hexiamond
- Hexlet
- Hexomino
- Heyting algebra
- Hi-Q
- Hierarchy
- Higgs field
- Higgs prime
- Higher arithmetic
- Higher-order function
- Highest common divisor
- Highest weight
- Highly abundant number
- Highly composite number
- Higman-Sims graph
- Higman-Sims group
- Hilbert algebra
- Hilbert basis
- Hilbert basis theorem or Hilbert Basis Theorem
- Hilbert class field
- Hilbert cube
- Hilbert curve
- Hilbert function
- Hilbert Hotel
- Hilbert infinite hotel
- Hilbert matrix
- Hilbert modular form
- Hilbert polynomial
- Hilbert problems
- Hilbert scheme
- Hilbert space
- Hilbert symbol
- Hilbert theorem
- Hilbert Theorem 90 or Hilbert theorem 90
- Hilbert transform
- Hilbert's Axioms or Hilbert's axioms
- Hilbert's irreducibility theorem
- Hilbert's Nullstellensatz
- Hilbert's paradox of the Grand Hotel
- Hilbert's problems or Hilbert's Problems
- Hilbert's sixteenth problem
- Hilbert's Theorem or Hilbert's theorem
- Hilbert's theorem 90 or Hilbert's Theorem 90
- Hilbert-Pólya conjecture
- Hilbert-Schmidt integral operator or Hilbert-schmidt integral operator
- Hilbert-Schmidt norm
- Hilbert-Schmidt operator
- Hilda Geiringer or Hilda geiringer
- Hill differential equation
- Hinge
- Hinge theorem
- Hippopede
- Hirzebruch L-polynomial
- Hirzebruch signature theorem
- Histogram
- Hitch
- Hitting set
- HNN extension
- HNN-extension
- Hodge conjecture
- Hodge cycle
- Hodge decomposition
- Hodge diamond
- Hodge Star or Hodge star
- Hodge star operator
- Hodge structure
- Hodge theorem
- Hodge theory
- Hodge variety
- Hodge's theorem
- Hodograph
- Hoffman-Singleton Graph or Hoffman-Singleton graph
- Holder inequality or Hölder inequality
- Holditch's theorem
- Hole
- Holography
- Holomorphic form
- Holomorphic function
- Holomorphic line bundle
- Holomorphic map
- Holomorphic mapping
- Holomorphic vector bundle
- Holomorphically convex
- Holonomic constant
- Holonomic function
- Holonomy
- Holonomy group
- Holor
- Holyhedron
- Hom
- Home Plate or Home plate
- Homeomorphic
- Homeomorphism
- Homeomorphism (graph theory)
- Homeomorphism group
- Homeotopy
- Homer
- HOMFLY polynomial or Homfly polynomial
- Homoclinic
- Homogeneous
- Homogeneous coordinates
- Homogeneous equation
- Homogeneous function
- Homogeneous ideal
- Homogeneous polynomial
- Homogeneous space
- Homographic
- Homography
- Homological Algebra or Homological algebra
- Homologous
- Homology
- Homology (mathematics)
- Homology class
- Homology functor
- Homology group
- Homology manifold
- Homology sphere
- Homology theory
- Homomorphic
- Homomorphism or *-homomorphism
- Homoscedastic
- Homoscedasticity
- Homothecy
- Homothetic
- Homothety
- Homotopic
- Homotopy
- Homotopy class
- Homotopy equivalence
- Homotopy extension property
- Homotopy group
- Homotopy groups
- Homotopy lifting property
- Homotopy of maps
- Homotopy of paths
- Homotopy sphere
- Homotopy theory
- Homotopy type
- Honeycomb
- Honeycomb conjecture
- Hoof
- Hook
- Hooke law
- Hopf algebra
- Hopf Bifurcation or Hopf bifurcation
- Hopf bundle
- Hopf fibration
- Hopf invariant
- Hopf invariant one problem
- Hopf Invariant One Theorem or Hopf invariant one theorem
- Hopf link
- Hopf manifold
- Hopf map
- Hopf space
- Hopf-Rinow theorem
- Hopfian group
- Horizontal
- Horn clause
- Horn function
- Horn hypergeometric series
- Horn torus
- Horned sphere
- Horner scheme
- Horner's method
- Horner's rule
- Horocycle
- Horseshoe lemma or Horseshoe Lemma
- Horseshoe map
- Hosohedron
- Hotelling T2 distribution
- Hotelling's T-square distribution, Hotelling T2 distribution
- Hough transform or Hough Transform
- Householder matrix
- Householder transformation
- Hub
- Huffman code
- Huffman coding or Huffman Coding
- Huffman's algorithm
- Hull
- Hull number
- Hundred
- Hurst Exponent or Hurst exponent
- Hurwitz matrix
- Hurwitz polynomial
- Hurwitz theorem
- Hurwitz zeta function
- Hurwitz zeta-function
- Hurwitz's Irrational Number Theorem or Hurwitz's irrational number theorem
- Hurwitz's theorem
- Hurwitz-Radon theorem
- Huygens principle
- Hydra and Hercules
- Hydrogen-like atom
- Hyman Bass
- Hypatia
- Hyper-elliptic curve
- Hyper-elliptic integral
- Hyper-Kähler manifold
- Hyperbola
- Hyperbolic angle
- Hyperbolic cosecant
- Hyperbolic cosine
- Hyperbolic cosine integral
- Hyperbolic cotangent
- Hyperbolic fixed point
- Hyperbolic functions
- Hyperbolic geometry
- Hyperbolic group
- Hyperbolic inverse functions
- Hyperbolic knot
- Hyperbolic map
- Hyperbolic paraboloid
- Hyperbolic partial differential equation
- Hyperbolic plane
- Hyperbolic polar sine
- Hyperbolic secant
- Hyperbolic set
- Hyperbolic sine
- Hyperbolic sine integral
- Hyperbolic space
- Hyperbolic spiral
- Hyperbolic tangent
- Hyperbolic trigonometry
- Hyperboloid
- Hypercohomology
- Hypercomplex number
- Hyperconnected space
- Hypercube
- Hypercycle
- Hyperdodecahedron
- Hyperedge
- Hyperellipse
- Hyperelliptic curve
- Hyperelliptic function
- Hyperelliptic integral
- Hyperelliptic surface
- Hyperfactorial
- Hyperflex
- Hyperfunction
- Hypergeometric differential equation
- Hypergeometric distribution
- Hypergeometric equation
- Hypergeometric function
- Hypergeometric identity
- Hypergeometric series
- Hypergeometric summation
- Hypergraph
- Hypericosahedron
- Hyperkähler manifold
- Hyperoctahedron
- Hyperperfect number
- Hyperplane
- Hyperplane arrangement
- Hyperreal
- Hyperreal number
- Hypersine
- Hyperspace
- Hypersphere
- Hypersurface
- Hypertext
- Hypertext Markup Language or Hypertext markup language
- Hypervolume
- Hyphen
- Hypocycloid
- Hypoellipse
- Hypoelliptic
- Hypotenuse
- Hypothesis
- Hypothesis testing
- Hypotrochoid
- Hysteresis
- Hénon attractor
- Hénon map
- Hölder condition
- Hölder mean
- Hölder space
