Origin of sigmaClassical Greek
- The 18th letter of the Greek alphabet. alphabet
- A sigma factor.
- Statistics The standard deviation of a given probability distribution or a given set of data.
Origin of sigmaGreek sīgma of Phoenician origin smk
- The name for the eighteenth letter of the Classical and Modern Greek, the twentieth letter of Old and Ancient.
- (mathematics) The symbol Σ, used to indicate summation of a set or series.
- (statistics) The symbol σ, used to indicate one standard deviation from the mean, particularly in a normal distribution.