Definition of "sigma" in Anglais

noun

1. The eighteenth letter of the Classical and Modern Greek alphabets (Σ, σ), the twentieth letter of Old and Ancient.

2. (mathematics) The symbol Σ, used to indicate summation of a set or series.

3. (statistics) The symbol σ, used to indicate one standard deviation from the mean, particularly in a normal distribution.

   • 2011, Paul Rincon, (bbc.co.uk) LHC: Higgs boson 'may have been glimpsed' None of the spikes seen by the experiments is at much more than the "two sigma" level of certainty. A level of "five sigma" is required to claim a discovery, meaning there is less than a one in a million chance the data spike is down to a statistical fluke.

4. (Internet slang) A sigma male (a self-reliant and assertive male).

adjective

1. (Internet slang) Possessing characteristics of a sigma male.