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
Greek alphabet Caroline Winterer states is "understandable, considering that general knowledge of the ancient Greek alphabet and language has almost entirely vanished." Some letters can occur in variant shapes, mostly inherited from medieval minuscule handwriting. While their use in normal typography of Greek is purely a matter of font styles, some such variants have been given separate encodings in Unicode. For computer usage, a variety of encodings have been used for Greek online, many of them documented in . The two principal ones still used today are ISO/IEC 8859-7 and Unicode. ISO 8859-7 supports only the monotonic orthography; Unicode supports both the