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 becoming the first 'true' alphabet. Apparently, some thirty years later, the same alphabet was introduced to Boeotia, having been adopted perhaps a little earlier in Macedonia, and went on in the course of the 4th century to displace the local alphabets throughout the whole Greek-speaking world. The Ionic alphabet included a new letter, omega, at the end of the alphabet, and standardised the representation of various sounds that had varied from one dialect to another, as follows: The absence of a letter for was of no consequence for the Ionic dialects, but sometimes led to ambiguities in Attic, which had