Chi (letter)

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"χ" and "Χ" redirect here. For the consonant represented by χ in IPA, see Voiceless uvular fricative."Khi" redirects here. For other uses, see KHI.Not to be confused with X, ×, or Ξ.

Chi ( /kaɪ/ ⓘ KY, also /xiː/ KHEE; [1] [2] uppercase Χ, lowercase χ; Greek : χῖ) is the twenty-second letter of the Greek alphabet.

Contents

Greek

The Greek alphabet on a black figure vessel, with a cross-shaped chi NAMA Alphabet grec.jpg
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 ([x]/[ç]) 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 some pronunciations of "h" in English words like 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 or Spanish j. This distinction corresponds to the ich-Laut and ach-Laut of German.

Transliteration

Chi is romanized as ⟨ch⟩ in most systematic transliteration conventions, but sometimes ⟨kh⟩ is used. [3] In addition, in Modern Greek, it is often also romanized 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 use of the letter X for the same sound in Latin, and many modern languages that use the Latin alphabet.

Cyrillic

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

International Phonetic Alphabet

In the International Phonetic Alphabet, ⟨χ⟩ represents a voiceless uvular fricative.

Chiasmus

Chi is the basis for the name literary chiastic structure and the name of chiasmus.

Symbolism

In Plato's Timaeus , it is explained that the two bands that form the soul of the world cross each other like the letter Χ. Plato's analogy, along with several other examples of chi as a symbol occur in Thomas Browne's discourse The Garden of Cyrus (1658).

Chi or X is often used to abbreviate the name Christ, as in the holiday Christmas (Xmas). When fused within a single typeface with the Greek letter rho, it is called the Chi Rho and used to represent the person of Jesus Christ.

Mathematics and science

Unicode

See also

References

  1. ↑ "chi". The Chambers Dictionary (9th ed.). Chambers. 2003. ISBN   0-550-10105-5.
  2. ↑ "chi" . Oxford English Dictionary (Online ed.). Oxford University Press.(Subscription or participating institution membership required.)
  3. ↑ "Greek language | Definition, Alphabet, Origin, & Facts | Britannica". www.britannica.com. 2024-12-20. Retrieved 2025-02-09. Some differences in transliteration result from changes in pronunciation of the Greek language; others reflect convention, as for example the χ (chi or khi), which was transliterated by the Romans as ch (because they lacked the letter k in their usual alphabet). In Modern Greek, however, the standard transliteration for χ is kh.
  4. ↑ Weisstein, Eric W. "Euler Characteristic". mathworld.wolfram.com. Retrieved 2025-02-09.
  5. ↑ Weisstein, Eric W. "Chromatic Number". mathworld.wolfram.com. Retrieved 2025-02-09. The chromatic number of a graph G is most commonly denoted χ (G) (e.g., Skiena 1990, West 2000, Godsil and Royle 2001, Pemmaraju and Skiena 2003),...
  6. ↑ Asimov, Isaac (1963). The Human Brain. Boston: Houghton Mifflin.
  7. ↑ Zumdahl, Steven S. (2008). Chemistry (8th ed.). Cengage Learning. p.  201. ISBN   978-0547125329.
  8. ↑ Spencer, James N.; Bodner, George M.; Rickard, Lyman H. (2010). Chemistry: structure and dynamics (5th ed.). Hoboken, NJ: Wiley. p.  357. ISBN   9780470587119.
  9. ↑ IUPAC , Compendium of Chemical Terminology , 5th ed. (the "Gold Book") (2025). Online version: (2006–) " Electronegativity ". doi : 10.1351/goldbook.E01990
  10. ↑ Mugiraneza, Sam; Hallas, Alannah M. (2022-04-19). "Tutorial: a beginner's guide to interpreting magnetic susceptibility data with the Curie-Weiss law". Communications Physics. 5 (1): 1–12. arXiv: 2205.07107 . doi:10.1038/s42005-022-00853-y. ISSN   2399-3650. However, for newly synthesized materials, there is one indispensable characterization technique that is as old as the field of magnetism itself: magnetic susceptibility, χ,...
  11. ↑ Jiles, David (2016). Introduction to magnetism and magnetic materials (Third ed.). Boca Raton London New York: CRC Press, Taylor & Francis Group. p. 42. ISBN   978-1-138-44149-1. We can now make a general statement for the permeability μ and susceptibility χ
  12. ↑ Unicode Code Charts: Greek and Coptic (Range: 0370-03FF)
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