Xi (letter) Xi (letter) Xi (uppercase Ξ, lowercase ξ; ) is the 14th letter of the Greek alphabet. It is pronounced in Modern Greek, and generally or in English. In the system of Greek numerals, it has a value of 60. Xi was derived from the Phoenician letter samekh . Xi is not to be confused with the letter chi, which gave its form to the Latin letter X. Both in classical Ancient Greek and in Modern Greek, the letter Ξ represents the sound . In some archaic local variants of the Greek alphabet, this letter was missing. Instead, especially in the
History of the alphabet Two variants of the Phoenician alphabet had major impacts on the history of writing: the Aramaic alphabet and the Greek alphabet. The Phoenician and Aramaic alphabets, like their Egyptian prototype, represented only consonants, a system called an "abjad". The Aramaic alphabet, which evolved from the Phoenician in the 7th century BCE, to become the official script of the Persian Empire, appears to be the ancestor of nearly all the modern alphabets of Asia: By at least the 8th century BCE the Greeks borrowed the Phoenician alphabet and adapted it to their own language, creating in the process the first "true"