# Six Sigma

> English word · Proper noun

## Definitions
1. A set of techniques and tools for process improvement.

## Etymology
A reference to the fraction of a normal curve that lies within six standard deviations of the mean, used to represent a defect rate.

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-05-06.
Canonical page: https://plainspell.com/en/word/six-sigma