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

See also