σ (EN)

letter, symbol

letter “σ”

1. the eighteenth letter of the Greek alphabet, lowercase sigma
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   In Greek language classes, students learn that σ is the lowercase form of sigma.

symbol “σ”

1. (mathematics) a symbol representing standard deviation in statistics
   The statistician calculated σ to understand how the data varied from the mean.
2. (physics) a symbol representing electrical conductivity
   The electrical conductivity σ increases with temperature in this material.
3. (physics) a symbol representing cross-sectional area
   The scattering cross-section σ is crucial in nuclear physics experiments.