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
Esh (letter) Esh (letter) Esh (majuscule: Ʃ Unicode U+01A9, minuscule: ʃ Unicode U+0283) is a character used in conjunction with the Latin script. Its lowercase form ʃ is similar to a long s ſ or an integral sign ∫; in 1928 the Africa Alphabet borrowed the Greek letter Sigma for the uppercase form Ʃ, but more recently the African reference alphabet discontinued it, using the lowercase esh only. The lowercase form was introduced by Isaac Pitman in his 1847 Phonotypic Alphabet to represent the voiceless postalveolar fricative (English "sh"). It is today used in the International Phonetic Alphabet, as well as in