Greek Character

Αα (alpha)

• α represents:
  • the first angle in a
    triangle, opposite the side a
  • the statistical
    significance of a result
  • the false positive rate
    in statistics (“Type I” error)
  • the fine-structure
    constant in physics
  • the angle of attack of an aircraft
  • an alpha particle (He²⁺)
  • angular acceleration in
    physics
  • the linear thermal expansion
    coefficient
  • the thermal diffusivity
  • In organic chemistry the
    α-carbon is the backbone carbon next to the carbonyl carbon,
    most often for amino acids
  • right ascension in
    astronomy
  • the brightest star in a constellation
  • Iron ferrite and numerous
    phases within materials science
  • the return in excess of the compensation for the risk
    borne in investment
  • the α-conversion in
    lambda calculus
  • the independence number of a
    graph
  • a placeholder for ordinal numbers
    in mathematical logic
  •  a type of receptor for the neurotransmitter
    noradrenaline in
    neuroscience

Ββ (beta)

• Β represents the beta function
• β represents:
  • the thermodynamic beta, equal
    to (k_BT)⁻¹, where k_B is
    the Boltzmann constant and T is the absolute temperature.
  • the second angle in a triangle, opposite
    the side b
  • the standardized regression
    coefficient for predictor
    or independent variables in linear
    regression (unstandardized
    regression coefficients are represented with the lower-case
    Latin b, but are often called “betas” as well)
  • the ratio of collector current to base current in a bipolar
    junction transistor (BJT) in
    electronics (current gain)
  • the false negative rate
    in statistics (“Type II” error)
  • the beta coefficient, the
    non-diversifiable risk, of an asset in mathematical
    finance
  • the sideslip angle of an airplane
  • a beta particle (e⁻ or
    e⁺)
  • the beta brain wave in brain or cognitive
    sciences
  • ecliptic latitude in
    astronomy
  • the ratio of plasma pressure to magnetic
    pressure in plasma
    physics
  • β-reduction in lambda
    calculus
  • the ratio of the velocity of an object to the speed of
    light as used in the Lorentz
    factor
  • a type of receptor for the
    noradrenaline neurotransmitter in
    neuroscience

Γγ (gamma)

• Γ represents:
  • the circulation in
    fluid dynamics
  • the reflection coefficient
    of a transmission or telecommunication line.
  • the confinement factor of an optical mode in a
    waveguide
  • the gamma function, a
    generalization of the factorial
  • the upper incomplete gamma
    function
  • the modular group, the group of
    fractional linear transformations
  • the gamma distribution, a
    continuous probability distribution defined using the gamma
    function
  • second-order sensitivity to
    price in mathematical
    finance
  • the Christoffel symbols that
    describe components of a metric connection
  • the stack alphabet in the formal definition of a pushdown
    automaton, or the tape-alphabet
    in the formal definition of a Turing
    machine
  • the Feferman–Schütte
    ordinal Γ₀
• γ represents:
  • the specific weight of substances
  • the lower incomplete gamma
    function
  • the third angle in a triangle, opposite
    the side c
  • the Euler–Mascheroni
    constant in mathematics
  • gamma rays and the
    photon
  • the heat capacity ratio in
    thermodynamics
  • the Lorentz factor in special
    relativity
  • the flight path angle of
    an airplane

Δδ (delta)

• Δ represents:
  • a finite difference
  • a difference operator
  • a symmetric difference
  • the Laplace operator
  • giving heat in a chemical
    reaction
  • the angle that subtends the arc of a circular curve in
    surveying
  • the maximum degree of any
    vertex in a given
    graph
  • sensitivity to price in
    mathematical finance
  • the discriminant of a polynomial (in
    a quadratic polynomial determines the nature of the roots)
• δ represents:
  • percent error
  • a variation in the calculus of
    variations
  • the Kronecker delta function
  • the Feigenbaum constants
  • the force of interest in
    mathematical finance
  • the Dirac delta function
  • the receptor which
    enkephalins have the highest affinity
    for in pharmacology[1]
  • the Skorokhod integral in
    Malliavin calculus, a subfield
    of stochastic analysis
  • the minimum degree of any
    vertex in a given
    graph
  • a partial charge. δ− represents a
    negative partial charge, and δ+ represents a positive partial
    charge chemistry (See also:
    Solvation)
  • the chemical shift of an atomic
    nucleus in NMR spectroscopy. For
    protons, this is relative to
    tetramethylsilane = 0
  • stable isotope
    compositions
  • declination in
    astronomy
  • noncentrality measure in statistics[2]
  • The transition function in the formal definition of a finite
    automaton, pushdown
    automaton, or Turing
    machine
  • Infinitesimal - see
• Not to be confused with ∂ which is based on the
  Latin letter d but often called a “script delta”

Εε (epsilon)

• ϵ represents:
  • a small positive quantity; see
    limit
  • a random error in regression
    analysis
  • the absolute value of an error[3]
  • in set theory, the limit
    ordinal of the sequence
    ω, ω^ω, ω^ωω, …
  • in computer science, the empty
    string
  • the Levi-Civita symbol
  • in electromagnetics,
    dielectric
    permittivity
  • emissivity
  • strain in continuum
    mechanics
  • permittivity
  • the Earth’s axial tilt in
    astronomy
  • elasticity in
    economics
  • electromotive force
  • in chemistry, the molar extinction
    coefficient of a
    chromophore
  • in mathematics, a surreal number
    that is bigger than zero, but smaller than all the non-negative
    numbers.
• set membership symbol ∈ is based on
  ε

(digamma)

• is sometimes used to represent the digamma
  function, though the Latin letter F
  (which is nearly identical) is usually substituted.

• A hypothetical particle Ϝ speculated to be implicated in the
  750 GeV diphoton
  excess, now known to be
  simply a statistical anomaly

Ζζ (zeta)

• ζ represents:
  • the Riemann zeta function
    and other zeta
    functions in
    mathematics
  • the damping ratio
  • the value for the Zeta potential,
    i.e., the electrical potential at the slipping plane, used often
    in colloidal chemistry

Ηη (eta)

• Η represents:
  • the Eta function of Ludwig
    Boltzmann’s
    H-theorem (“Eta” theorem), in
    statistical mechanics
  • Information theoretic (Shannon)
    entropy
• η represents:
  • the intrinsic wave impedance of a
    medium (e.g. the impedance of free
    space)
  • the partial regression
    coefficient in statistics, also
    interpreted as an effect size measure
    for analyses of variance
  • the eta meson
  • viscosity
  • the Dedekind eta function
  • energy conversion
    efficiency
  • efficiency
    (physics)
  • the Minkowski metric tensor in
    relativity
  • η-conversion in
    lambda calculus
  • the learning rate in machine
    learning and statistics

Θθ (theta)

• Θ (uppercase) represents:

  • an asymptotically tight bound related to big O
    notation.
  • sensitivity to the passage of
    time in mathematical
    finance
  • in set theory, a certain ordinal
    number
  • Heaviside step function

• θ (lowercase) represents:

  • a plane angle in
    geometry
  • the angle to the x
    axis in the
    xy-plane in
    spherical or cylindrical
    coordinates (mathematics)
  • the angle to the z
    axis in spherical
    coordinates (physics)
  • the potential temperature in
    thermodynamics
  • theta functions
  • the angle of a scattered photon during a Compton
    scattering interaction
  • the angular displacement of a
    particle rotating about an axis
  • the Watterson estimator in
    population genetics

• (“script theta”), the cursive form of theta, often used in
  handwriting, represents

  • the first Chebyshev function in
    number theory
  • Theta role in linguistics

Ιι (iota)

• ι represents:
  • an inclusion map in set
    theory
  • the index generator function in
    APL (in the form ⍳)
  • the interior product

Κκ (kappa)

• Κ represents:
  • the Kappa number, indicating lignin
    content in pulp
• κ represents:
  • the Von Kármán constant,
    describing the velocity profile of turbulent flow
  • the kappa curve, a two-dimensional
    algebraic curve
  • the condition number of a
    matrix in numerical
    analysis
  • the connectivity of a
    graph in graph
    theory
  • curvature
  • dielectric constant
    (ε/ε₀)
  • thermal conductivity (usually
    a lowercase Latin k)
  • electrical conductivity of
    a solution
  • thermal diffusivity
  • a spring constant (usually a
    lowercase Latin k)
  • the heat capacity ratio in
    thermodynamics (usually γ)
  • the receptor which
    dynorphins have the highest affinity
    for in pharmacology[4]
  • Einstein gravitational
    constant

Λλ (lambda)

• Λ represents:
  • the Lebesgue constant, a bound
    for the interpolation error
  • the von Mangoldt function in
    number theory
  • the set of logical axioms in the axiomatic
    method of logical deduction in
    first-order logic
  • the cosmological constant
  • the lambda baryon
  • a diagonal matrix of eigenvalues in
    linear algebra
  • a lattice
  • molar conductivity in
    electrochemistry
  • Iwasawa algebra
• λ represents:
  • one wavelength of electromagnetic
    radiation
  • the decay constant in radioactivity
  • function expressions in the lambda
    calculus
  • a general eigenvalue in linear
    algebra
  • the expected number of occurrences in a Poisson
    distribution in probability
  • the arrival rate in queueing
    theory
  • the failure rate in reliability
    engineering
  • the Lagrange multiplier in
    mathematical
    optimization, known as
    the shadow price in economics
  • the Lebesgue measure denotes the
    volume or measure of a Lebesgue measurable set
  • longitude in
    geodesy
  • linear density
  • ecliptic longitude in
    astronomy
  • the Liouville function in
    number theory
  • the Carmichael function in
    number theory
  • the empty string in formal
    grammar
  • a formal system (lambda calculus)
    in mathematical logic
  • thermal conductivity
  • the Lorentz
    transformation

Μμ (mu)

• μ represents:
  • the Möbius function in number
    theory
  • the population mean or expected
    value in
    probability and
    statistics
  • a measure in measure
    theory
  • micro-, an SI
    prefix denoting 10⁻⁶ (one
    millionth)
  • Micrometre or micron (retired in 1967
    as a standalone symbol, replaced by “μm” using the standard SI
    meaning)
  • the coefficient of
    friction in
    physics
  • the service rate in queueing
    theory
  • the dynamic viscosity in physics
  • magnetic
    permeability in
    electromagnetics
  • a muon
  • reduced mass
  • the ion mobility in plasma
    physics
  • the Standard gravitational
    parameter in
    celestial mechanics
  • population mean in
    statistics
  • chemical potential in
    thermodynamics
  • Absorption coefficient
  • Amplification factor
  • Magnetic moment of a
    dipole

Νν (nu)

• ν represents:
  • frequency in physics in
    hertz (Hz)
  • Poisson’s ratio in materials
    science
  • a neutrino
  • kinematic viscosity of liquids
  • stoichiometric
    coefficient in chemistry
  • true anomaly in celestial
    mechanics
  • degrees of freedom
    in statistics
  • the matching number of a
    graph
  • the p-adic valuation of a number

Ξξ (xi)

• Ξ represents:
  • the original Riemann Xi
    function, i.e. Riemann’s lower
    case ξ, as denoted by Edmund Landau
    and currently
  • the xi baryon
• ξ represents:
  • the original Riemann Xi
    function
  • the modified definition of Riemann xi function, as denoted by
    Edmund Landau
  • the extent of reaction

Οο (omicron)

Ππ (pi)

• Π represents:
  • the product
    operator in mathematics
  • a plane
  • the unary projection operation in relational
    algebra
  • the Pi function, i.e. the Gamma
    function when offset to coincide
    with the factorial
  • the complete elliptic integral of the third
    kind
  • the fundamental groupoid
  • osmotic pressure
• π represents:
  • Archimedes’ constant (more
    commonly just called Pi), the ratio of a
    circle’s
    circumference to its
    diameter
  • the prime-counting
    function
  • the state distribution of a Markov
    chain
  • in reinforcement learning,
    a policy function defining how a software
    agent behaves for each possible
    state of its environment
  • a type of covalent bond in chemistry
    (pi bond)
  • a pion (pi meson) in particle physics
  • in statistics, the population
    proportion
  • nucleotide diversity in
    molecular genetics
  • in electronics, a special type of small signal
    model is referred to as a
    hybrid-pi model
  • in discrete mathematics, a permutation
  • Projection
• ϖ (a graphic variant, see pomega) represents:
  • angular frequency of a
    wave, in fluid
    dynamics (angular frequency is
    usually represented by ω but this may be confused with
    vorticity in a fluid dynamics context)
  • longitude of pericenter,
    in astronomy[5]
  • comoving distance, in
    cosmology[6]

Ρρ (rho)

• Ρ represents:
  • one of the Gegenbauer functions
    in analytic number theory (may be replaced by the capital form
    of the Latin letter P).
• ρ represents:
  • one of the Gegenbauer functions
    in analytic number theory.
  • the Dickman-de Bruijn function
  • the radius in a
    polar,
    cylindrical, or
    spherical coordinate
    system
  • the correlation
    coefficient
    in statistics
  • the radius of convergence in
    real analysis[7]
  • the sensitivity to interest
    rate in mathematical
    finance
  • density (mass or charge per unit volume;
    may be replaced by the capital form of the Latin letter D)
  • resistivity
  • the shape and reshape operators in
    APL (in the form ⍴)
  • the rename operator in
    relational
    algebra
  • the plastic ratio
  • Rho meson

Σσς (sigma)

• Σ represents:
  • the summation operator
  • the covariance matrix
  • the set of terminal symbols in a
    formal grammar
  • Mathematical surface
  • Sigma baryon
• σ represents:
  • Stefan–Boltzmann
    constant in blackbody
    radiation
  • the divisor function in number
    theory
  • the real part of the
    complex variable s = σ + i**t
    in analytic number theory
  • the sign of a permutation in the
    theory of finite groups
  • the population standard
    deviation, a measure of
    spread in
    probability and
    statistics
  • a type of covalent bond in chemistry
    (sigma bond)
  • the selection operator in relational
    algebra
  • stress in mechanics
  • electrical conductivity
  • area density
  • Cross section
    • nuclear cross section
  • surface charge density for
    microparticles
  • standard deviation of a random
    variable in
    statistics
  • Spectrum of a matrix
  • Spin

Ττ (tau)

• τ represents:
  • torque, the net rotational force in
    mechanics
  • the elementary tau lepton in particle
    physics
  • a mean lifetime, of an exponential
    decay or spontaneous
    emission process
  • the time constant of any device,
    such as an RC circuit
  • proper time in
    relativity
  • one turn: the
    constant ratio of a
    circle’s
    circumference to its
    radius, with value 2π (6.283…).[8]
  • Kendall tau rank correlation
    coefficient,
    a measure of rank correlation in
    statistics
  • Ramanujan’s tau function
    in number theory
  • shear stress in continuum
    mechanics
  • a type variable in type theories, such as the simply typed
    lambda calculus
  • path tortuosity in reservoir
    engineering
  • in topology, a given topology
  • the tau in
    biochemistry, a
    protein associated to
    microtubules
  • the number of divisors of highly composite numbers
  • precision
    (τ²), the reciprocal of
    variance, in
    statistics

ϒυ (upsilon)

• Υ (U+03D2) represents:
  • the upsilon meson

Φφ (phi)

• Φ represents:
  • the work function in physics; the
    energy required by a photon to remove an electron from the
    surface of a metal
  • magnetic flux or electric
    flux
  • the cumulative distribution
    function of the
    normal distribution in
    statistics
  • phenyl functional group in organic
    chemistry (pseudoelement
    symbol)
  • the reciprocal of the
    golden ratio (represented by ϕ,
    below), also represented as 1/ϕ
  • the value of the integration of information in a system (based
    on integrated information
    theory)
  • Geopotential
  • Alternative symbol for a wave
    function in quantum
    mechanics

Note: The empty set symbol ∅ looks similar, but
is unrelated to the Greek letter.

• ϕ or φ represents:
  • the golden ratio 1.618… in
    mathematics, art, and architecture
  • Euler’s totient function
    in number theory
  • the argument of a complex number in
    mathematics
  • the value of a plane angle in physics and
    mathematics
  • the angle to the z
    axis in spherical
    coordinates (mathematics)
  • epoch or phase difference between
    two waves or vectors
  • the angle to the x
    axis in the
    xy-plane in
    spherical or cylindrical
    coordinates (physics)
  • latitude in geodesy
  • radiant flux
  • neutron flux
  • Potential energy
  • electric potential
  • a scalar field in quantum field
    theory
  • the probability density
    function of the
    normal distribution in
    statistics
  • the Veblen functions

Χχ (chi)

• χ represents:
  • the chi distribution in
    statistics (χ² is the more
    frequently encountered chi-squared
    distribution)
  • the chromatic number of a graph
    in graph theory
  • the Euler characteristic in
    algebraic topology
  • electronegativity in the
    periodic table
  • the Fourier transform of a linear response
    function
  • a character in
    mathematics; especially a Dirichlet
    character in number
    theory
  • sometimes the mole fraction
  • a characteristic or indicator
    function in mathematics
  • the magnetic
    susceptibility of a
    material in physics
  • the fission neutron energy spectrum in neutron
    transport

Ψψ (psi)

• Ψ represents:
  • water potential
  • a quaternary combinator in combinatory
    logic
  • a symbol for psychology
• ψ represents:
  • the wave function in the
    Schrödinger equation of
    quantum mechanics
  • the psi mesons in particle physics
  • the stream function in fluid
    dynamics
  • the reciprocal Fibonacci
    constant
  • the second Chebyshev function
    in number theory
  • the polygamma function in
    mathematics
  • the supergolden ratio[9]

Ωω (omega)

• Ω represents:
  • Absolute infinite
  • the SI unit measure of electrical
    resistance, the
    ohm
  • the right ascension of the ascending
    node (RAAN)
    or Longitude of the ascending
    node in
    astronomy and orbital
    mechanics
  • the omega constant
    0.5671432904097838729999686622…
  • an asymptotic lower bound notation related to big O
    notation
  • in probability theory and
    statistical mechanics, the
    support
  • a solid angle
  • the omega baryon
  • the arithmetic
    function
    counting a number’s prime factors counted with multiplicity
  • the density parameter in
    cosmology
  • the first uncountable
    ordinal (also written as
    ω₁)
  • Chaitin’s constant for a given
    computer program
  • the vacuum state in quantum
    field theory
• ω represents:
  • angular velocity / radian
    frequency (rad/sec)
  • the argument of periapsis in
    astronomy and orbital
    mechanics
  • a complex
    cube root of
    unity — the other is ω²
    — (used to describe various ways of calculating the discrete
    Fourier transform)
  • the differentiability class (i.e. C^ω) for
    functions that are infinitely differentiable because they are
    complex analytic
  • the first infinite
    ordinal
  • the omega meson
  • the set of natural numbers in set
    theory (although ℕ or N is more
    common in other areas of mathematics)
  • an asymptotic dominant notation related to big O
    notation
  • in probability theory, a
    possible outcome of an experiment
  • the arithmetic
    function
    counting a number’s distinct prime factors
  • the symbol ϖ, a graphic variant of π, is sometimes construed as
    omega with a bar over it; see π
  • the unsaturated fats nomenclature
    in biochemistry (e.g. ω−3 fatty
    acids)
  • the first uncountable ordinal ω₁ (also written as
    Ω)
  • the clique number (number of
    vertices in a maximum clique) of a graph in graph
    theory