sigma

 
Pronunciation: /ˈsɪgmə/

noun

  • the eighteenth letter of the Greek alphabet (Σ, σ), transliterated as ‘s’.
    • The form ς is used instead of σ at the end of a word. The uncial form, resembling the letter c, is also sometimes used
  • (Sigma) [followed by Latin genitive] Astronomy the eighteenth star in a constellation: Sigma Octantis
  • Chemistry & Physics relating to or denoting an electron or orbital with zero angular momentum about an internuclear axis: the σ orbital is localized symmetrically

symbol

  • (Σ) mathematical sum.
  • (σ) standard deviation.

Origin:

Greek