Sigma (disambiguation)

Look up sigma in Wiktionary, the free dictionary.

Sigma (Σ,σ) is a letter of the Greek alphabet.

Sigma may also refer to:

Places

SIGMA (verification service), Nielsen Media Research's tracking system for videos
Sigma AB, a Swedish IT consultancy company
Sigma Corporation, a Japanese camera and lens manufacturer
Sigma Designs, Inc., a US semiconductor manufacturer
Sigma Motor Corporation, a South African motor vehicle assembler and manufacturer
Sigma Pharmaceuticals, an Australian pharmaceutical company
Sigma Sport, a German manufacturer of electronic sports equipment
Sigma TV, a television channel in Cyprus
Sigma-Aldrich, an American chemical company
Telkomsigma or Sigma Cipta Caraka, an Indonesian ICT business solution provider

Stefan–Boltzmann constant of radiation in physics σ
Sigma factor of RNA polymerase in biology σ
In the Hammett equation, the electronic substituent constant σ for activation of substituted arenes
Sigma baryon, in particle physics
Pauli matrices in quantum physics
Cross section σ in physics
Sigma bond in chemistry σ
Sigma receptor, a neural receptor
Electrical conductivity, a measure of a material's ability to conduct electricity σ
Stress (mechanics), the force per unit area applied by internal forces of a material σ

Ood Sigma, a fictional character from the Doctor Who series
Theta Sigma, the nickname of the fictional character the Doctor from the Doctor Who series, given during his training at the Academy on the planet Gallifrey
Space City Sigma, a 1980s Indian science fiction TV series