sigma

• Nom désignant la dix-huitième lettre de l'alphabet grec.

A noun referring to the 18th letter of the Greek alphabet.

1. Greek letterB1formal

   The 18th letter of the Greek alphabet, often used in mathematics and science.

   sigma (lettre grecque)

   • The symbol sigma is used to denote summation in mathematics.
   • In statistics, sigma represents the standard deviation.
   • The Greek letter sigma looks like a capital E in its uppercase form.