Sigma (Greek letter)

| Main Article
| Discussion
| Related Articles  [?]
| Bibliography  [?]
| External Links  [?]
| Citable Version  [?]

|
|
|
|
|
|
|
|

This editable Main Article is under development and subject to a disclaimer.

[edit intro]

Sigma is the 18th letter of the Greek alphabet. It is written as  Σ {\displaystyle \Sigma } (upper-case) and  σ {\displaystyle \sigma } (lower-case), except at the end of a word, where the lower-case form is ς instead.