Definition

1. Noun:
   • The 18th letter of the Greek alphabet: "Sigma" is the name of the 18th letter in the Greek alphabet, written as Σ (uppercase) or σ/ς (lowercase). It is used in writing the Greek language and as a symbol in various academic and scientific fields.

Examples of Usage

• Noun:
  • In the Greek word "σχολή" (school), the first letter is a lowercase sigma.
  • The uppercase sigma (Σ) is often used in mathematics to denote summation.

Advanced Usage

• Statistics: In statistics, the lowercase sigma (σ) represents the standard deviation of a population, a measure of data dispersion.
  • A low sigma value indicates that the data points are close to the mean.
• Physics and Engineering: Sigma is used to denote various constants, such as electrical conductivity or surface charge density.
  • The Stefan-Boltzmann constant in physics is represented by the symbol σ.
• Final Form (ς): In Greek typography, the lowercase sigma has a special form (ς) used only when the letter appears at the end of a word.
  • The word "δός" (give) ends with the final sigma (ς).

Variants and Related Words

• Six Sigma (n): A set of techniques and tools for process improvement, originally developed in manufacturing.
  • The company implemented Six Sigma methodologies to reduce defects.

Synonyms

• Greek letter: A general term for any character in the Greek alphabet, of which sigma is one.

Related Phrases

• Sigma male (n): A modern, informal term from social theory describing a male who is introverted, self-reliant, and operates outside traditional social hierarchies. (Note: This is a compound term using "sigma").
  • The article discussed the archetype of the sigma male in contemporary culture.

Noun

1. the 18th letter of the Greek alphabet