Psi (letter) Psi (letter) Psi (; uppercase ', lowercase '; "psi" ) is the 23rd letter of the Greek alphabet and has a numeric value of 700. In both Classical and Modern Greek, the letter indicates the combination /ps/ (as in English word "lapse"). For Greek loanwords in Latin and modern languages with Latin alphabets, psi is usually transliterated as "ps". The letter's origin is uncertain. It may or may not derive from the Phoenician alphabet. It appears in the 7th century BC, expressing /ps/ in the Eastern alphabets, but /kʰ/ in the Western alphabets (the sound expressed by Χ in the
History of the Greek alphabet Midas. This link may have facilitated the Greeks "borrowing" their alphabet from the Phrygians because the Phrygian letter shapes are closest to the inscriptions from Aeolis. Some scholars argue for earlier dates: Naveh (1973) for the 11th century BC, Stieglitz (1981) for the 14th century, Bernal (1990) for the 18th–13th century, some for the 9th, but none of these are widely accepted. According to legends recounted by Herodotus, the alphabet was first introduced to Greece by a Phoenician named Cadmus: Herodotus estimates that Cadmus lived sixteen hundred years earlier, or around 2000 BC. He had seen and described the Cadmean