Sigma
/ˈsɪɡ.mə/noun
The eighteenth letter of the Greek alphabet, written Σ or σ, with a final form ς.
Did you know?Sigma’s lowercase form σ changes to ς at the end of a Greek word, while its uppercase form Σ became the symbol for summation in mathematics.
Etymological Timeline
1st millennium BCE
Phoenician
𐤎
“A Phoenician letter traditionally identified as the ancestral sign of Greek sigma; its original name and meaning remain debated.”
8th–6th Century BCE
Archaic Greek
𐌑 / Ϻ
“Early Greek sigma forms, adopted into the Greek alphabet and used for the /s/ sound.”
Classical Greek
Ancient Greek
σίγμα
“The name of the Greek letter sigma.”
Hellenistic Greek
Ancient Greek
Σ, σ, ς
“Standardized uppercase, lowercase, and word-final forms of the letter.”
17th Century
European mathematics
Σ
“The capital sigma begins to be used as a symbol for summation, especially in mathematical notation.”
Modern English
English
sigma
“The Greek letter, its mathematical summation symbol, or a statistical measure such as standard deviation.”