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  any angle, reference angle, direction angle (x-axis), significance level (probability of a type I error); sometimes: proportional to Beta Beta function, Beta distribution any angle, direction angle (y-axis), probability of a type II error, beta distribution, regression coefficient
Gamma Gamma function, Gamma distribution any angle, direction angle (z-axis), Euler's constant, gamma distribution
Delta any change in a quantity Kronecker's delta, Dirac delta function, infinitesimal change
Epsilon  any positive quantity (especially a very small one)
Zeta  Riemann zeta function
Eta  Theta  any angle
Iota  Kappa  curvature of a function
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  (statistics) population mean, (mensuration) SI prefix "micro-"
Nu  Xi  Riemann Xi Function
Omicron  Pi product operator, ( ) Coproduct operator Pi (constant), the ratio between a circle's diameter and circumference approximately , Prime counting function
Rho  Degree of a vertex, radius in spherical coordinates, radius of curvature of a function
Sigma summation operator standard deviation
Tau  Torsion of a curve, suggested as a constant representing the ratio between a circle's radius and circumference, equal to 2π
Upsilon  Phi  φ ( ), angle between z-axis and radius in spherical coordinates
Chi  (statistics) Chi-squared test
Psi  Polygamma Function
Omega  