Chi (letter) for the design of steel structures. In graph theory, a lowercase chi is used to represent a graph's chromatic number. Chi (letter) Chi (uppercase Χ, lowercase χ; ) is the 22nd letter of the Greek alphabet, pronounced or in English. Its value in Ancient Greek was an aspirated velar stop (in the Western Greek alphabet: /ks/). In Koine Greek and later dialects it became a fricative (/) along with Θ and Φ. In Modern Greek, it has two distinct pronunciations: In front of high or front vowels ( or ) it is pronounced as a voiceless palatal fricative , as
Coptic alphabet accepted to separate it, with the proposal noting that Coptic is never written using modern Greek letter-forms (unlike German, which may be written with Fraktur or Roman Antiqua letter-forms), and that the Coptic letter-forms have closer mutual legibility with the Greek-based letters incorporated into the separately encoded Cyrillic alphabet than with the forms used in modern Greek. In Old Coptic, there were a large number of Demotic Egyptian characters, including some logograms. They were soon reduced to half a dozen, for sounds not covered by the Greek alphabet. The following letters remained: In Unicode, most Coptic letters formerly shared codepoints