sigma

  1. Noun.  The name for the eighteenth letter of the Classical and Modern Greek, the nineteenth letter of Old and Ancient.
  2. Noun.  (mathematics) The symbol '''Σ''', used to indicate summation of a set or series.
  3. Noun.  (statistics) The symbol '''σ''', used to indicate one standard deviation from the mean, particularly in a normal distribution.

This is an unmodified, but possibly outdated, definition from Wiktionary and used here under the Creative Commons license. Wiktionary is a great resource. If you like it too, please donate to Wikimedia.

This entry was last updated on RefTopia from its source on 3/20/2012.