San (Ϻ) was an archaic letter of the Greek alphabet. Its shape was similar to modern M, or to a modern Greek Sigma (Σ) turned sideways, and it was used as an alternative to Sigma to denote the sound /s/. Unlike Sigma, whose position in the alphabet is between Rho and Tau, San appeared between Pi and Qoppa in alphabetic order. In addition to denoting this separate archaic character, the name "San" was also used as an alternative name to denote the standard letter Sigma.