Sigma is the 18th letter within the Greek alphabet. Pronounced with an “s” sound, Sigma is often present in arithmetic, science, and engineering, representing summation, normal deviation, and stress, respectively.
When saying Sigma, keep in mind to make use of a tough “s” sound just like the one in “sin” or “sit.” Keep away from saying Sigma with a tender “s” sound just like the one in “measure” or “pleasure.” The emphasis must be on the primary syllable, so pronounce it “SIG-muh.”