From Textus Receptus
In Modern Greek, it has two distinct pronunciations: In front of high or front vowels (/e/ or /i/) it is pronounced as a voiceless palatal fricative [ç], as in German ich or like the h in some pronunciations of the English words hew and human. In front of low or back vowels (/a/, /o/ or /u/) and consonants, it is pronounced as a voiceless velar fricative ([x]), as in German ach. Chi is Romanized as <ch> in most systematic transliteration conventions, but also sometimes as <h> or <x> in informal practice.
In the system of Greek numerals, it has a value of 600.
In ancient times, some local forms of the Greek alphabet used the chi instead of xi to represent the /ks/ sound. This was borrowed into the early Latin language, which led to the letter X being used for the same sound in Latin, and the modern languages which use the Latin alphabet.
International Phonetic Alphabet
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.
Math and science
The optic chiasm, an x-shaped connection of the optic nerves leading to the eye, got its name from the letter chi because of its shape; likewise, the shape of the letter chi is the origin of the rhetorical device chiasmus.
- 1. Asimov, Isaac (1963). The Human Brain. Boston: Houghton Mifflin.