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
Coptic alphabet of Greek origin; 6 or 7 more were retained from Demotic, depending on the dialect (6 in Sahidic, another each in Bohairic and Akhmimic). In addition to the alphabetic letters, the letter ϯ stood for the syllable or . As the Coptic alphabet is simply a typeface of the Greek alphabet, with a few added letters, it can be used to write Greek without any transliteration schemes. Latin equivalents would include the Icelandic alphabet (which likewise has added letters), or the Fraktur alphabet (which has distinctive forms). While initially unified with the Greek alphabet by Unicode, a proposal was later