Σ

Σ U+03A3, Σ GREEK CAPITAL LETTER SIGMA [unassigned: U+03A2] ← Ρ [U+03A1] Greek and Coptic Τ → [U+03A4]

Σ

1. (mathematics) Σ. Sum over a set of like terms:

   ${\displaystyle \sum _{n=1}^{3}n^{2}=1^{2}+2^{2}+3^{2}=14}$

2. (topology) suspension or reduced suspension
3. (mathematics) A class (in the arithmetical hierarchy) of formulae whose outermost unbounded quantifiers are existential quantifiers

(mathematics): Though there exists a distinct symbol (∑) for the purpose of the mathematical summation, the upper case sigma here is often used for convenience.

• (classification of formulae): Π, Δ

• Σ on Wikipedia.Wikipedia

• Ϲ (S)

From Phoenician 𐤔 (š, “šīn”).

Σ • (S) (uppercase, nonfinal lowercase σ, final lowercase ς)

1. The letter sigma (σίγμα), the 18th letter of the ancient Greek alphabet.

• (Cyrillic) С
• (Coptic) Ⲥ

• (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 • (S) (uppercase, lowercase σ)

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

Σ • (S)

1. The number 200 in Greek numerals.

,Σ

1. The number 200,000 in Greek numerals.

see: Appendix:Greek alphabet