σ

See also: ς, Σ, σ., and σ'

σ U+03C3, σ GREEK SMALL LETTER SIGMA ← ς [U+03C2] Greek and Coptic τ → [U+03C4]

𝜎 U+1D70E, 𝜎 MATHEMATICAL ITALIC SMALL SIGMA ← 𝜍 [U+1D70D] Mathematical Alphanumeric Symbols 𝜏 → [U+1D70F]

Translingual

Symbol

σ

1. (mathematics, statistics) Standard deviation.
2. (mathematics) Sum of divisors.
3. (mathematics) Braid group algebra.
4. (physics, scattering) Cross section.
5. (linguistics, phonology) Syllable.
6. (phonology, obsolete) a labialized alveolar fricative (value uncertain, possibly IPA [θʷ]).
7. (spatial databases) The select operation.
8. (physics) The Stefan-Boltzmann constant.
9. (chemistry) A shielding constant.

Ancient Greek

Alternative forms

• ϲ (s) — lunate sigma
• ς (s) — word-final position

Etymology

Derived from its majuscule counterpart Σ.

Letter

σ • (s) (lowercase, uppercase Σ)

1. Lower-case sigma (σίγμα), the 18th letter of the ancient Greek alphabet. It represented the voiceless alveolar fricative /s/. It is preceded by ρ and followed by τ.

Derived terms

See also sigma

• σ΄, ͵σ
• с, С (Cyrillic)
• ⲥ, Ⲥ (Coptic)

See also

• (Greek-script letters) Α α, Β β, Γ γ, Δ δ, Ε ε, Ζ ζ, Η η, Θ θ, Ι ι, Κ κ, Λ λ, Μ μ, Ν ν, Ξ ξ, Ο ο, Π π, Ρ ρ, Σ σ ς, Τ τ, Υ υ, Φ φ, Χ χ, Ψ ψ, Ω ω
• (non-Classical letters) Ϝ ϝ, Ͷ ͷ, Ͱ ͱ, Ϻ ϻ, Ϙ ϙ, Ͳ ͳ
• (punctuation) · ;
• (diacritics) ᾿ ῾ ◌́ ◌̀ ῀ ¨

Greek

Alternative forms

• ς (s) (only at the end of a word)

Letter

σ • (s) (lowercase, uppercase Σ)

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

See also

• (Greek-script letters) Α α, Β β, Γ γ, Δ δ, Ε ε, Ζ ζ, Η η, Θ θ, Ι ι, Κ κ, Λ λ, Μ μ, Ν ν, Ξ ξ, Ο ο, Π π, Ρ ρ, Σ σ ς, Τ τ, Υ υ, Φ φ, Χ χ, Ψ ψ, Ω ω
• (non-Classical letters) Ϝ ϝ, Ͷ ͷ, Ͱ ͱ, Ϻ ϻ, Ϙ ϙ, Ͳ ͳ
• (punctuation) · ;
• (diacritics) ᾿ ῾ ◌́ ◌̀ ῀ ¨
• σ΄
• ͵σ