sigma

noun

sig·​ma ˈsig-mə How to pronounce sigma (audio)
plural sigmas
1
: the 18th letter of the Greek alphabet see Alphabet Table
2
: standard deviation
3
slang : a person who is coolly self-assured, independent, and driven
Unlike alpha males and females who thrive on social dominance, sigmas prefer solitude and operate outside of traditional social hierarchies.—Gayathri Kallukaran
I know nowadays, everyone's trying to be a sigma, no one wants to admit any kind of fear …—Adam Richman
—often used before another noun
a sigma male/female
I'm what's called a sigma personality. I never seek leadership. I fill in where I see a need.—@imsarahbella, on X, formerly Twitter
… the two [movies] have the same loner, dark, depressed sigma vibe …—@3RBlank, on Reddit
 compare alpha entry 1 sense 6, beta entry 1 sense 2b

Examples of sigma in a Sentence

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
This is a figure known as five sigma, which equates to about a one in a million chance that the findings are a fluke. — Oliver Swainston, Space.com, 28 June 2025 While the signal is there at three sigma, that's three sigma above a completely featureless spectrum. — John Timmer, ArsTechnica, 17 Apr. 2025 The consequences are fatal, and the silence and sigma surrounding it has become part of the problem. — Sreedhar Potarazu, Baltimore Sun, 6 July 2025 Existing models put to the test The combined data from all three radio telescopes revealed a deviation higher than five sigma—a very strong signal. — Chris Young, Interesting Engineering, 14 Nov. 2025 The company has made innovations in write assist, stability assist, pioneering high-sigma design modeling to capture tail bits and row plus column redundancy to enable low voltages and high overall yields. — Thomas Coughlin, Forbes.com, 3 Sep. 2025 Should 5 sigma be reached, Heymans said astronomers should expect to see similar results in data from the Euclid Space Telescope, which is slated to do a similar experiment to DESI, at higher redshift, in the near future. — Jennifer Ouellette, Ars Technica, 19 Mar. 2025 That range spans about 370 parts-per-billion between the various estimates, with some overlapping with Fermilab’s experimental data and others, particularly from the older R-ratio methods, disagreeing with Fermilab’s data at greater than the 5-sigma threshold. — Big Think, 19 Mar. 2026

Word History

Etymology

Greek

First Known Use

1550, in the meaning defined at sense 1

Time Traveler
The first known use of sigma was in 1550

Rhymes for sigma

See All Rhymes for sigma

Browse Nearby Words

siglum
sigma
sigmaspire
See all Nearby Words

Cite this Entry

“Sigma.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/sigma. Accessed 7 Jul. 2026.

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Kids Definition

sigma

noun
sig·​ma ˈsig-mə How to pronounce sigma (audio)
: the 18th letter of the Greek alphabet
—Σ or σ or ς
Last Updated: - Updated example sentences
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