σ

See also: ς, ϲ, Σ, σ̌, σ̑, σ., σ’, and ƍ

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

Character variations

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

Translingual

Symbol

σ

1. (mathematics, statistics) Population standard deviation.

   Coordinate term: s

2. (mathematics) Sum of divisors.
3. (mathematics) Braid group algebra.
4. (physics, scattering) Cross section.
6. (materials science) tensile stress.

   Coordinate term: τ (shear stress)

7. (linguistics, phonology) Syllable.

   Synonym: $

8. (IPA, obsolete) a labialized alveolar fricative: identified as IPA [θʷ] or [sᶲ], equivalent to Shona ⟨ȿ⟩.

   See also: ƍ

9. (spatial databases) The select operation.
10. (physics) The Stefan-Boltzmann constant.
11. (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 (W) ϝ (w), Ͷ ͷ, Ͱ (H) ͱ (h), Ϻ (S) ϻ (s), Ϟ ϟ, Ϙ (Q) ϙ (q), Ͳ (S) ͳ (s)
• (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 (W) ϝ (w), Ͷ ͷ, Ͱ (H) ͱ (h), Ϻ (S) ϻ (s), Ϟ ϟ, Ϙ (Q) ϙ (q), Ͳ (S) ͳ (s)
• (punctuation) · ⸳ . ;
• (diacritics) ᾿ ῾ ◌́ ◌̀ ῀ ¨
• σ΄
• ͵σ