Standard deviation in statistics σ

Sigma (chemistry), the electronic substituent constant of molecules in physical chemistry σ

Six Sigma, a quality management program

A busy beaver function in computability theory Σ

Mitsubishi Sigma, motor car, a variant of the Galant

Sigma (Mega Man X), villain in the Mega Man X video game series

Sigma baryon, a class of baryons in particle physics

Sigma receptor, a subtype of opioid receptor

Summation operator forming a series in mathematics Σ

Pauli matrices in quantum physics

Sigma factor of RNA polymerase in biology σ

Sigma (Σ, σ, or ς), of the Greek alphabet

Divisor function in number theory σ

Sigma-algebra (σ-algebra, σ-field) in set theory

Sigma Corporation, a Japanese camera and lens manufacturer.

Sigma-Aldrich Corporation

Stefan-Boltzmann constant of radiation in physics σ

Sigma TV a television channel in Cyprus.

Sigma summary and related information.

Sigma bond in chemistry σ

GM Sigma platform, a mid-size car automobile platform from General Motors Corporation

Smith & Wesson Sigma, a Smith & Wesson firearm

Sigma Company, an Australian company. Its main operations include Pharmaceuticals and Pharmacies.

Sigma Company Limited, a Hungarian debt management company.

Sigma, Capiz, a municipality in the Philippines

SIGMA (verification service), Nielsen Media Research's tracking system for videos