σ

Symbol

 * 1)  Standard deviation.
 * 2)  Sum of divisors.
 * 3)  Braid group algebra.
 * 4)  Cross section.
 * 5)  Syllable.
 * 6)  a labialized alveolar fricative (value uncertain, possibly IPA ).
 * 7)  The select operation.
 * 8)  The Stefan-Boltzmann constant.
 * 9)  A shielding constant.

Etymology
Derived from its majuscule counterpart Σ.

Letter

 * 1) Lower-case sigma, the 18th letter of the ancient Greek alphabet. It represented the  . It is preceded by ρ and followed by τ.

Derived terms
See also sigma

Letter

 * 1) The lower case letter sigma (σίγμα), the 18th letter of the modern Greek alphabet.