Chi
(
uppercase Χ,
lowercase χ; el, χῖ) is the 22nd letter of the
Greek alphabet
The Greek alphabet has been used to write the Greek language since the late 9th or early 8th century BCE. It is derived from the earlier Phoenician alphabet, and was the earliest known alphabetic script to have distinct letters for vowels as ...
.
Greek
Pronunciation
Ancient Greek
Its value in
Ancient Greek
Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic pe ...
was an aspirated
velar stop (in the
Western Greek alphabet: /ks/).
Koine Greek
In
Koine Greek
Koine Greek (; Koine el, ἡ κοινὴ διάλεκτος, hē koinè diálektos, the common dialect; ), also known as Hellenistic Greek, common Attic, the Alexandrian dialect, Biblical Greek or New Testament Greek, was the common supra-reg ...
and later dialects it became a
fricative
A fricative is a consonant produced by forcing air through a narrow channel made by placing two articulators close together. These may be the lower lip against the upper teeth, in the case of ; the back of the tongue against the soft palate in ...
(/) along with
Θ and
Φ.
Modern Greek
In
Modern Greek
Modern Greek (, , or , ''Kiní Neoellinikí Glóssa''), generally referred to by speakers simply as Greek (, ), refers collectively to the dialects of the Greek language spoken in the modern era, including the official standardized form of the ...
, it has two distinct pronunciations: In front of
high
High may refer to:
Science and technology
* Height
* High (atmospheric), a high-pressure area
* High (computability), a quality of a Turing degree, in computability theory
* High (tectonics), in geology an area where relative tectonic uplift t ...
or
front vowels ( or ) it is pronounced as a
voiceless palatal fricative , as in
German
German(s) may refer to:
* Germany (of or related to)
**Germania (historical use)
* Germans, citizens of Germany, people of German ancestry, or native speakers of the German language
** For citizens of Germany, see also German nationality law
**Ge ...
''ich'' or like the ''h'' in some pronunciations of the
English
English usually refers to:
* English language
* English people
English may also refer to:
Peoples, culture, and language
* ''English'', an adjective for something of, from, or related to England
** English national ...
words ''hew'' and ''human''. In front of
low or
back vowels (, or ) and
consonants, it is pronounced as a
voiceless velar fricative
The voiceless velar fricative is a type of consonantal sound used in some spoken languages. It was part of the consonant inventory of Old English and can still be found in some dialects of English, most notably in Scottish English, e.g. in ''loc ...
(), as in German ''ach'' or
Spanish ''j''.
Transliteration
Chi is
romanized as in most systematic transliteration conventions, but sometimes is used. In addition, in Modern Greek, it is often also romanized as or in informal practice.
Greek numeral
In the system of
Greek numerals
Greek numerals, also known as Ionic, Ionian, Milesian, or Alexandrian numerals, are a system of writing numbers using the letters of the Greek alphabet. In modern Greece, they are still used for ordinal numbers and in contexts similar to those ...
, it has a value of 600.
Xi
In ancient times, some
local forms of the
Greek alphabet
The Greek alphabet has been used to write the Greek language since the late 9th or early 8th century BCE. It is derived from the earlier Phoenician alphabet, and was the earliest known alphabetic script to have distinct letters for vowels as ...
used the chi instead of
xi to represent the /ks/ sound. This was borrowed into the early
Latin
Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through ...
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
The Latin alphabet or Roman alphabet is the collection of letters originally used by the ancient Romans to write the Latin language. Largely unaltered with the exception of extensions (such as diacritics), it used to write English and the ...
.
Cyrillic
Chi was also included in the
Cyrillic script
The Cyrillic script ( ), Slavonic script or the Slavic script, is a writing system used for various languages across Eurasia. It is the designated national script in various Slavic, Turkic, Mongolic, Uralic, Caucasian and Iranic-speaking c ...
as the letter
Х, with the phonetic value /x/ or /h/.
International Phonetic Alphabet
In the
International Phonetic Alphabet
The International Phonetic Alphabet (IPA) is an alphabetic system of phonetic notation based primarily on the Latin script. It was devised by the International Phonetic Association in the late 19th century as a standardized representation ...
, the minuscule chi is the symbol for the
voiceless uvular fricative.
Chiasmus
Chi is the basis for the name literary
chiastic structure and the name of
chiasmus.
Symbolism
In
Plato
Plato ( ; grc-gre, Πλάτων ; 428/427 or 424/423 – 348/347 BC) was a Greek philosopher born in Athens during the Classical period in Ancient Greece. He founded the Platonist school of thought and the Academy, the first institution ...
'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
''The Garden of Cyrus'', or ''The Quincuncial Lozenge, or Network Plantations of the Ancients, naturally, artificially, mystically considered'', is a discourse by Sir Thomas Browne. First published in 1658, along with its diptych companion '' Ur ...
'' (1658).
Chi or
X is often used to abbreviate the name
Christ
Jesus, likely from he, יֵשׁוּעַ, translit=Yēšūaʿ, label= Hebrew/ Aramaic ( AD 30 or 33), also referred to as Jesus Christ or Jesus of Nazareth (among other names and titles), was a first-century Jewish preacher and relig ...
, as in the holiday
Christmas
Christmas is an annual festival commemorating the birth of Jesus Christ, observed primarily on December 25 as a religious and cultural celebration among billions of people around the world. A feast central to the Christian liturgical year ...
(
Xmas). When fused within a single typespace with the Greek letter
rho
Rho (uppercase Ρ, lowercase ρ or ; el, ρο or el, ρω, label=none) is the 17th letter of the Greek alphabet. In the system of Greek numerals it has a value of 100. It is derived from Phoenician letter res . Its uppercase form uses the sa ...
, it is called the
labarum and used to represent the person of Jesus Christ.
Character encodings
Greek chi
Coptic khi
Latin chi
Mathematical chi
These characters are used only as mathematical symbols. Stylized Greek text should be encoded using the normal Greek letters, with markup and formatting to indicate text style.
Math and science
In
statistics
Statistics (from German: '' Statistik'', "description of a state, a country") is the discipline that concerns the collection, organization, analysis, interpretation, and presentation of data. In applying statistics to a scientific, indust ...
, the term chi-squared or
has
various uses, including the
chi-squared distribution
In probability theory and statistics, the chi-squared distribution (also chi-square or \chi^2-distribution) with k degrees of freedom is the distribution of a sum of the squares of k independent standard normal random variables. The chi-squar ...
, the
chi-squared test
A chi-squared test (also chi-square or test) is a statistical hypothesis test used in the analysis of contingency tables when the sample sizes are large. In simpler terms, this test is primarily used to examine whether two categorical variables ...
, and
chi-squared target models.
In
algebraic topology
Algebraic topology is a branch of mathematics that uses tools from abstract algebra to study topological spaces. The basic goal is to find algebraic invariants that classify topological spaces up to homeomorphism, though usually most classify ...
, Chi is used to represent the
Euler characteristic of a surface.
In
neuroanatomy,
crossings of
peripheral nerves (such as the
optic chiasm) are named for the letter Chi because of its Χ-shape.
In
chemistry
Chemistry is the scientific study of the properties and behavior of matter. It is a natural science that covers the elements that make up matter to the compounds made of atoms, molecules and ions: their composition, structure, proper ...
, the
mole fraction and
electronegativity may be denoted by the lowercase
.
In
physics
Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which ...
,
denotes
electric or
magnetic susceptibility.
In
rhetoric, both
chiastic structure (a
literary device) and the
figure of speech Chiasmus derive from their names from the shape of the letter Chi.
In
mechanical engineering
Mechanical engineering is the study of physical machines that may involve force and movement. It is an engineering branch that combines engineering physics and mathematics principles with materials science, to design, analyze, manufacture, ...
, chi is used as a symbol for the
reduction factor
Reduction, reduced, or reduce may refer to:
Science and technology Chemistry
* Reduction (chemistry), part of a reduction-oxidation (redox) reaction in which atoms have their oxidation state changed.
** Organic redox reaction, a redox react ...
of relevant
buckling loads in the
EN 1993, a
European Standard for the design of steel structures.
In
graph theory
In mathematics, graph theory is the study of '' graphs'', which are mathematical structures used to model pairwise relations between objects. A graph in this context is made up of '' vertices'' (also called ''nodes'' or ''points'') which are conn ...
, a lowercase chi is used to represent a graph's
chromatic number.
See also
{{Wiktionary, Χ, χ
*
Chi (disambiguation)
*
Х, х - Kha (Cyrillic)
References
Greek letters
Phonetic transcription symbols