sigma

Definition

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

Etymology

From Ancient Greek σῖγμα (sîgma), probably from the root σῑγ- (sīg-) as seen in σίζω (sízō, “to hiss”) + -μα (-ma, nominal suffix).

Example Sentences

• "Their names, which are expressive of some bodily or mental excellence, all end with the same letter---the letter which is called San by the Dorians, and Sigma by the Ionians."
• "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."