Chi (letter)

Greek alphabet
Αα	Alpha	Νν	Nu
Ββ	Beta	Ξξ	Xi
Γγ	Gamma	Οο	Omicron
Δδ	Delta	Ππ	Pi
Εε	Epsilon	Ρρ	Rho
Ζζ	Zeta	Σσς	Sigma
Ηη	Eta	Ττ	Tau
Θθ	Theta	Υυ	Upsilon
Ιι	Iota	Φφ	Phi
Κκ	Kappa	Χχ	Chi
Λλ	Lambda	Ψψ	Psi
Μμ	Mu	Ωω	Omega
History
Archaic local variants  ·  ·  ·  ·  ·
Ligatures (ϛ, ȣ, ϗ) · Diacritics
Numerals: (6) · (90) · (900)
In other languages
Bactrian  · Coptic  · Albanian
Scientific symbols
Book  · Category · Commons view · talk · edit

Chi (uppercase Χ, lowercase χ; Greek: χῖ) is the 22nd letter of the Greek alphabet, pronounced as /ˈkaɪ/ in English.

Greek

The Greek alphabet on a black figure vessel, with a cross-shaped chi.

Pronunciation

Ancient Greek

Its value in Ancient Greek was an aspirated velar stop /kʰ/ (in the Western Greek alphabet: /ks/).

Koine Greek

In Koine Greek and later dialects it became a fricative along with Θ and Φ.

Modern Greek

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.

Greek numeral

In the system of Greek numerals, it has a value of 600.

Xi

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.

Cyrillic

Chi was also included in the Cyrillic alphabet as the letter Х, with the phonetic value /x/ or /h/.

International Phonetic Alphabet

In the International Phonetic Alphabet, chi is the symbol for the voiceless uvular fricative.

Chiasmus

Chi is the basis for the name Chiastic structure and the name of Chiasmus.

Symbolism

In Plato's Timaeus, it is explained that the two bands which form the soul of the world cross each other like the letter Χ.

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

Chi is also frequently used in statistics.

In Algebraic Topology, Chi is used to represent the Euler Characteristic of a surface.

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;^[1] likewise, the shape of the letter chi is the origin of the rhetorical device chiasmus.

In EN 1993, an European Standard for the design of steel structures, the chi character is used as a symbol for the reduction factor for the relevant buckling load.

References

1. ^ Asimov, Isaac (1963). The Human Brain. Boston: Houghton Mifflin. 

See also

• Chi (disambiguation)
• Х, х - Kha (Cyrillic)