ASCII Character χ
Greek small letter chiChi /ˈkaɪ, ˈxiː/ (uppercase Χ, lowercase χ; Greek: χῖ) is the 22nd letter of the Greek alphabet. Its value in Ancient Greek was an aspirated velar stop /kʰ/ (in the Western Greek alphabet: /ks/). In the system of Greek numerals, it has a value of 600. Chi was also included in the Cyrillic script as the letter Х, with the phonetic value /x/ or /h/. Chi or X is often used to abbreviate the name Christ, as in the holiday Christmas (Xmas). When fused within a single typespace with the Greek letter rho, it is called the labarum and used to represent the person of Jesus Christ.