1. the eighteenth letter of the Greek alphabet (Σ, σ)
2. a symbol used in mathematics to represent summation
Usage: mathematics
3. a measure of standard deviation in statistics
Usage: statistics

Examples

• The Greek letter sigma appears in many mathematical formulas.
• Students learn to write both uppercase and lowercase sigma in Greek class.
• The sigma notation makes it easier to express long sums.
• In the equation, sigma represents the sum of all terms.
• The data showed a sigma value of 2.5 for this distribution.
• Quality control uses six sigma methodology to reduce defects.
• The professor explained how sigma measures variability in the dataset.