sigma
Americannoun
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the 18th letter of the Greek alphabet: Σ, σ, ς.
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the consonant sound represented by this letter.
noun
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the 18th letter in the Greek alphabet (Σ, σ, or, when final, ς), a consonant, transliterated as S
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maths the symbol Σ, indicating summation of the numbers or quantities indicated
Etymology
Origin of sigma
First recorded in 1600–10; from Latin, from Greek sígma
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
In scientific jargon that is a five sigma result.
From BBC • Apr. 16, 2025
If you’re lurking in dark corners of the internet, there’s alpha, beta and sigma males.
From Salon • Oct. 14, 2023
One is a putative chitobiase that the UAB researchers found was located next to genes encoding SusD, SusC, putative anti-sigma factor and RNA polymerase ECF-type sigma factor.
From Science Daily • Oct. 13, 2023
At the time, the discrepancy between theory and experiment was, in particle-physics parlance, 4.2 sigma.
From Scientific American • Aug. 10, 2023
Il paro�t m�me qu'en divers endroits, o� ces vein�s ont la forme d'un sigma ou d'une M couch�e M, ce sont les grandes jambes du sigma, qui ont la direction des couches.
From Modern Painters, Volume IV (of V) by Ruskin, John
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
