The Greek alphabet is used extensively in mathematics and the physical sciences to stand for well known constants, variables, functions, and so forth. Because many of the uppercase (or capital, or majuscule) Greek letters are indistinguishable from their counterparts in the Latin alphabet, only uses that are specifically interpreted as Greek letters should be listed below.

Name Uppercase Lowercase
Symbol Meaning Symbol Meaning
Alpha \Alpha \alpha any angle, reference angle, direction angle (x-axis), significance level (probability of a type I error); sometimes: proportional to (\propto)
Beta \Beta Beta function, Beta distribution \beta any angle, direction angle (y-axis), probability of a type II error, beta distribution, regression coefficient
Gamma \Gamma Gamma function, Gamma distribution \gamma any angle, direction angle (z-axis), Euler's constant, gamma distribution
Delta \Delta any change in a quantity \delta Kronecker's delta, Dirac delta function, infinitesimal change
Epsilon \Epsilon \epsilon any positive quantity (especially a very small one)
Zeta \Zeta \zeta Riemann zeta function
Eta \Eta \eta
Theta \Theta \theta any angle
Iota \Iota \iota
Kappa \Kappa \kappa curvature of a function
Lambda \Lambda \lambda (Physics) Half-life, (physics) wave-length, (differential equations) zeros of a characteristic equation, (linear algebra) eigenvalues, (probability) parameter in the Poisson distribution, Lambda Calculus
Mu \Mu \mu (statistics) population mean, (mensuration) SI prefix "micro-"
Nu \Nu \nu
Xi \Xi \xi Riemann Xi Function
Omicron \Omicron \omicron
Pi \Pi product operator, (\coprod) Coproduct operator \pi Pi (constant), the ratio between a circle's diameter and circumference approximately 3.141592653\ldots, Prime counting function
Rho \Rho \rho Degree of a vertex, radius in spherical coordinates, radius of curvature of a function
Sigma \Sigma summation operator \sigma standard deviation
Tau \Tau \tau Torsion of a curve, suggested as a constant representing the ratio between a circle's radius and circumference, equal to 2π
Upsilon \Upsilon \upsilon
Phi \Phi \phi φ (1.618033988\ldots), angle between z-axis and radius in spherical coordinates
Chi \Chi \chi (statistics) Chi-squared test
Psi \Psi \psi Polygamma Function
Omega \Omega \omega

See also