Xi (letter) dialects of most of the Greek mainland and Euboea, the sound [ks] was represented by Χ (which in classical Greek is chi, used for ). Because this variant of the Greek alphabet was used in Italy, the Latin alphabet borrowed Χ rather than Ξ as the Latin letter X. While having no Latin derivative, the Xi was adopted into the early Cyrillic alphabet, as the letter ksi (Ѯ, ѯ). The uppercase letter Ξ is used as symbol for: The lowercase letter ξ is used as a symbol for: These characters are used only as mathematical symbols. Stylized Greek text should
History of the Greek alphabet them from certain digraphs which had become homophonous, as follows: The letters of the alphabet were used in the system of Greek numerals. For this purpose the letters digamma and qoppa (but not san) were retained although they had gone out of general use, and the obscure letter sampi was added at the end of the alphabet. Digamma was often replaced in numerical use by stigma (Ϛ), originally a ligature of sigma and tau, or even the sequence sigma-tau (στ'). The Old Italic and Anatolian alphabets are, like the Greek alphabet, attested from the 8th century BC. It is unclear