The term 'Sigma Preceder' is a combination of two Greek letters, Sigma and Rho. Sigma is the 18th letter of the Greek alphabet and is represented by the symbol Σ. Rho is the 17th letter of the Greek alphabet and is represented by the symbol ρ. Together, Sigma and Rho form the term Sigma Preceder, which is often used in mathematics and physics to refer to a mathematical operation or process that precedes another.