Uses of Greek Letters
Scientists and engineers employ Greek letters to represent a wide variety of quantities. This reduces ambiguity and distinguishes special constants from ordinary variables. The list below summarises common applications for each letter. Click on a letter’s name to visit its dedicated page.
Alpha (Α α)
- angles in geometry and trigonometry
- coefficients and attenuation constants
- area or angles in physics
Beta (Β β)
- phase or propagation constants in physics
- coefficients in mathematics
- beta particles in nuclear physics
Gamma (Γ γ)
- complex propagation constants
- specific gravity and conductivity
- Euler's gamma function
Delta (Δ δ)
- increment or change in calculus
- determinants and discriminants
- density and permittivity (Δ)
Epsilon (Ε ε)
- dielectric constant and permittivity
- small positive quantity in calculus
- strain in engineering
Zeta (Ζ ζ)
- Riemann zeta function
- damping ratio in engineering
- coordinates in science
Eta (Η η)
- intrinsic impedance
- efficiency in thermodynamics
- surface charge density
Theta (Θ θ)
- angles and angular phase
- time constants
- reluctance in physics
Iota (Ι ι)
- unit vectors
- small quantity in mathematics
Kappa (Κ κ)
- thermal conductivity
- coupling coefficient and susceptibility
Lambda (Λ λ)
- wavelength in physics
- permeance in electromagnetism
- eigenvalues in linear algebra
Mu (Μ μ)
- permeability and amplification factor
- coefficient of friction
- mean of a population
Nu (Ν ν)
- frequency in physics
- kinematic viscosity
Xi (Ξ ξ)
- random variables
- damping ratio and resistivity
Omicron (Ο ο)
- short vowel sound; limited scientific use
Pi (Π π)
- circle ratio π ≈ 3.1416…
- product notation in mathematics
- prime counting function
Rho (Ρ ρ)
- density in physics
- correlation coefficient in statistics
- radius of curvature
Sigma (Σ σ)
- summation operator (Σ)
- standard deviation and stress
- leakage coefficient and surface charge density
Tau (Τ τ)
- torque and shear stress
- lifetime in nuclear physics
- time constant in engineering
Upsilon (Υ υ)
- baryons in particle physics
- hyperbolic functions
- amplitude ratios
Phi (Φ φ)
- scalar potential (Φ)
- magnetic flux
- angles and porosity
Chi (Χ χ)
- electric susceptibility
- chi‑squared distribution
- angles in physics
Psi (Ψ ψ)
- wave functions in quantum mechanics
- phase difference and angles
- dielectric flux
Omega (Ω ω)
- unit of electrical resistance (ohm, Ω)
- angular velocity and solid angle
- Big‑Omega notation in complexity theory