noun
sigma
SIHG-muh
noun
1
The eighteenth letter of the Greek alphabet (Σ, σ).
"Sigma appears in the equation as the summation symbol."
2
In statistics, the symbol used to represent standard deviation from a mean.
"The result fell within two sigma of the expected value."
3
Slang for a self-reliant, emotionally detached man who operates outside conventional social hierarchies (a "sigma male").
"The video jokingly called the lone wolf character a total sigma."
How to Use Sigma
Learner’s notesIn plain EnglishA Greek letter used heavily in maths and science for summation and standard deviation, and, in recent internet slang, a personality-type label.
When to use it
The "sigma male" sense is internet slang and best kept to casual or ironic contexts.
Word Forms
more sigma comparative, sigmas plural, sigmata plural, most sigma superlative
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_____ appears in the equation as the summation symbol.
Etymology
From Ancient Greek sigma, likely from a root associated with hissing sounds, referencing the letter's "s" sound.