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 Greek alphabet of an upright and less ornamented style of writing more like Latin print. In 1982, the monotonic orthography was officially adopted, abandoning the rough and smooth breathings (since the sound had long since disappeared) and reducing the three types of accent mark to one (since the tone accent had been replaced by a stress accent). Greek pronunciation has also changed considerably since ancient times, but these changes have not been apparent from the orthography, which has remained conservative — see Greek alphabet for a summary of the current situation. The names of some letters were changed in order to distinguish