Chi ( , also ;
uppercase Χ, lowercase χ; ) is the twenty-second letter of the
Greek alphabet
The Greek alphabet has been used to write the Greek language since the late 9th or early 8th century BC. It was derived from the earlier Phoenician alphabet, and is the earliest known alphabetic script to systematically write vowels as wel ...
.
Greek
Pronunciation
Ancient Greek
Its value in
Ancient Greek
Ancient Greek (, ; ) includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Greek ...
was an aspirated
velar stop
In phonetics and phonology, a velar stop is a type of consonantal sound, made with the back of the tongue in contact with the soft palate (also known as the velum, hence velar), held tightly enough to block the passage of air (hence a stop consona ...
(in the
Western Greek alphabet
Many local variants of the Greek alphabet were employed in ancient Greece during the Archaic Greece, archaic and Classical Greece, early classical periods, until around 400 BC, when they were replaced by the classical 24-letter alphabet that ...
: /ks/).
Koine Greek
In
Koine Greek
Koine Greek (, ), also variously known as Hellenistic Greek, common Attic, the Alexandrian dialect, Biblical Greek, Septuagint Greek or New Testament Greek, was the koiné language, common supra-regional form of Greek language, Greek spoken and ...
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 , ), 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 language sometimes referred to ...
, 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 vowel
A front vowel is a class of vowel sounds used in some spoken languages, its defining characteristic being that the highest point of the tongue is positioned approximately as far forward as possible in the mouth without creating a constriction th ...
s ( or ) it is pronounced as a
voiceless palatal fricative
The voiceless palatal fricative is a type of consonantal sound used in some spoken languages. The symbol in the International Phonetic Alphabet that represents this sound is , and the equivalent X-SAMPA symbol is C. It is the non-sibilant equiv ...
, as in
German ''ich'' or like
some pronunciations of "h" in English words like ''hew'' and ''human''. In front of
low
Low or LOW or lows, may refer to:
People
* Low (surname), listing people surnamed Low
Places
* Low, Quebec, Canada
* Low, Utah, United States
* Lo Wu station (MTR code LOW), Hong Kong; a rail station
* Salzburg Airport (ICAO airport code: LO ...
or
back vowel
A back vowel is any in a class of vowel sound used in spoken languages. The defining characteristic of a back vowel is that the highest point of the tongue is positioned relatively back in the mouth without creating a constriction that would be c ...
s (, or ) and
consonants
In articulatory phonetics, a consonant is a speech sound that is articulated with complete or partial closure of the vocal tract, except for the h sound, which is pronounced without any stricture in the vocal tract. Examples are and pronou ...
, 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 ''lo ...
(), as in German ''ach'' or
Spanish ''j''. This distinction corresponds to the ich-Laut and ach-Laut of German.
Transliteration
Chi is
romanized
In linguistics, romanization is the conversion of text from a different writing system to the Roman (Latin) script, or a system for doing so. Methods of romanization include transliteration, for representing written text, and transcription, ...
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, is a numeral system, system of writing numbers using the letters of the Greek alphabet. In modern Greece, they are still used for ordinal number (linguistics), ordi ...
, 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 BC. It was derived from the earlier Phoenician alphabet, and is the earliest known alphabetic script to systematically write vowels as wel ...
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 spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...
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, also known as the Roman alphabet, is the collection of letters originally used by the Ancient Rome, ancient Romans to write the Latin language. Largely unaltered except several letters splitting—i.e. from , and from � ...
.
Cyrillic
Chi was also included in the
Cyrillic script
The Cyrillic script ( ) is a writing system used for various languages across Eurasia. It is the designated national script in various Slavic languages, Slavic, Turkic languages, Turkic, Mongolic languages, Mongolic, Uralic languages, Uralic, 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 standard written representation ...
, represents a
voiceless uvular fricative
The voiceless uvular fricative is a type of consonantal sound that is used in some spoken languages. The symbol in the International Phonetic Alphabet that represents this sound is , the Greek chi. The sound is represented by (ex with underdo ...
.
Chiasmus
Chi is the basis for the name literary
chiastic structure
Chiastic structure, or chiastic pattern, is a literary technique in motif (narrative), narrative motifs and other textual passages. An example of chiastic structure would be two ideas, A and B, together with variants A' and B', being presented as ...
and the name of
chiasmus
In rhetoric, chiasmus ( ) or, less commonly, chiasm (Latin term from Greek , "crossing", from the Ancient Greek, Greek , , "to shape like the letter chi (letter), Χ"), is a "reversal of grammatical structures in successive phrases or clauses ...
.
Symbolism
In
Plato
Plato ( ; Greek language, Greek: , ; born BC, died 348/347 BC) was an ancient Greek philosopher of the Classical Greece, Classical period who is considered a foundational thinker in Western philosophy and an innovator of the writte ...
'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
Sir Thomas Browne ( "brown"; 19 October 160519 October 1682) was an English polymath and author of varied works which reveal his wide learning in diverse fields including science and medicine, religion and the esoteric. His writings display a d ...
'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 Thomas Browne concerned with the quincunx—a pattern of five points arranged in an ...
'' (1658).
Chi or
X is often used to abbreviate the name
Christ
Jesus ( AD 30 or 33), also referred to as Jesus Christ, Jesus of Nazareth, and many other names and titles, was a 1st-century Jewish preacher and religious leader. He is the Jesus in Christianity, central figure of Christianity, the M ...
, as in the holiday
Christmas
Christmas is an annual festival commemorating Nativity of Jesus, the birth of Jesus Christ, observed primarily on December 25 as a Religion, religious and Culture, cultural celebration among billions of people Observance of Christmas by coun ...
(
Xmas
Xmas (also X-mas) is a common abbreviation of the word ''Christmas''. It is sometimes pronounced , but ''Xmas'', and variants such as ''Xtemass'', originated as handwriting abbreviations for the typical pronunciation . The 'X' comes from the Gree ...
). When fused within a single typeface with the Greek letter
rho
Rho (; uppercase Ρ, lowercase ρ or ; or ) is the seventeenth letter of the Greek alphabet. In the system of Greek numerals it has a value of 100. It is derived from Phoenician alphabet, Phoenician letter resh . Its uppercase form uses the same ...
, it is called the
Chi Rho
The Chi Rho (☧, English pronunciation ; also known as ''chrismon'') is one of the earliest forms of the Christogram, formed by superimposing the first two (capital) letters—chi (letter), chi and rho (ΧΡ)—of the Greek (Romanization of ...
and used to represent the person of Jesus Christ.
Math and science
* In
statistics
Statistics (from German language, German: ', "description of a State (polity), state, a country") is the discipline that concerns the collection, organization, analysis, interpretation, and presentation of data. In applying statistics to a s ...
, the term chi-squared or
has
various uses, including the
chi-squared distribution
In probability theory and statistics, the \chi^2-distribution with k Degrees of freedom (statistics), degrees of freedom is the distribution of a sum of the squares of k Independence (probability theory), independent standard normal random vari ...
, the
chi-squared test
A chi-squared test (also chi-square or test) is a Statistical hypothesis testing, 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 w ...
, and
chi-squared target model
* 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 invariant (mathematics), invariants that classification theorem, classify topological spaces up t ...
, Chi is used to represent the
Euler characteristic
In mathematics, and more specifically in algebraic topology and polyhedral combinatorics, the Euler characteristic (or Euler number, or Euler–Poincaré characteristic) is a topological invariant, a number that describes a topological space's ...
of a surface.
* The
chromatic number
In graph theory, graph coloring is a methodic assignment of labels traditionally called "colors" to elements of a graph. The assignment is subject to certain constraints, such as that no two adjacent elements have the same color. Graph coloring i ...
of a graph in
graph theory
In mathematics and computer science, graph theory is the study of ''graph (discrete mathematics), graphs'', which are mathematical structures used to model pairwise relations between objects. A graph in this context is made up of ''Vertex (graph ...
* In
neuroanatomy
Neuroanatomy is the study of the structure and organization of the nervous system. In contrast to animals with radial symmetry, whose nervous system consists of a distributed network of cells, animals with bilateral symmetry have segregated, defi ...
,
crossings of
peripheral nerves
The peripheral nervous system (PNS) is one of two components that make up the nervous system of bilateral animals, with the other part being the central nervous system (CNS). The PNS consists of nerves and ganglia, which lie outside the brain a ...
(such as the
optic chiasm
In neuroanatomy, the optic chiasm, or optic chiasma (; , ), is the part of the brain where the optic nerves cross. It is located at the bottom of the brain immediately inferior to the hypothalamus. The optic chiasm is found in all vertebrates, ...
) 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 physical science within the natural sciences that studies the chemical elements that make up matter and chemical compound, compounds made of atoms, molecules a ...
, the
mole fraction
In chemistry, the mole fraction or molar fraction, also called mole proportion or molar proportion, is a quantity defined as the ratio between the amount of a constituent substance, ''ni'' (expressed in unit of moles, symbol mol), and the to ...
and
electronegativity
Electronegativity, symbolized as , is the tendency for an atom of a given chemical element to attract shared electrons (or electron density) when forming a chemical bond. An atom's electronegativity is affected by both its atomic number and the ...
may be denoted by the lowercase
.
* In
physics
Physics is the scientific study of matter, its Elementary particle, 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 whi ...
,
denotes
electric
Electricity is the set of physical phenomena associated with the presence and motion of matter possessing an electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described by Maxwel ...
or
magnetic susceptibility
In electromagnetism, the magnetic susceptibility (; denoted , chi) is a measure of how much a material will become magnetized in an applied magnetic field. It is the ratio of magnetization (magnetic moment per unit volume) to the applied magnet ...
.
* In
rhetoric
Rhetoric is the art of persuasion. It is one of the three ancient arts of discourse ( trivium) along with grammar and logic/ dialectic. As an academic discipline within the humanities, rhetoric aims to study the techniques that speakers or w ...
, both
chiastic structure
Chiastic structure, or chiastic pattern, is a literary technique in motif (narrative), narrative motifs and other textual passages. An example of chiastic structure would be two ideas, A and B, together with variants A' and B', being presented as ...
(a
literary device
A narrative technique (also, in fiction, a fictional device) is any of several storytelling methods the creator of a story uses,
thus effectively relaying information to the audience or making the story more complete, complex, or engaging. Some ...
) and the
figure of speech
A figure of speech or rhetorical figure is a word or phrase that intentionally deviates from straightforward language use or Denotation, literal meaning to produce a rhetorical or intensified effect (emotionally, aesthetically, intellectually, et ...
Chiasmus
In rhetoric, chiasmus ( ) or, less commonly, chiasm (Latin term from Greek , "crossing", from the Ancient Greek, Greek , , "to shape like the letter chi (letter), Χ"), is a "reversal of grammatical structures in successive phrases or clauses ...
derive from their names from the shape of the letter Chi.
* In
mechanical engineering
Mechanical engineering is the study of physical machines and mechanism (engineering), mechanisms that may involve force and movement. It is an engineering branch that combines engineering physics and engineering mathematics, mathematics principl ...
, 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 reacti ...
of relevant
buckling
In structural engineering, buckling is the sudden change in shape (Deformation (engineering), deformation) of a structural component under Structural load, load, such as the bowing of a column under Compression (physics), compression or the wrin ...
loads in the
EN 1993, a
European Standard
European Standards, sometimes called Euronorm (abbreviated EN, from the German name , "European Norm"), are technical standards which have been ratified by one of the three European Standards Organizations (ESO): European Committee for Standardizat ...
for the design of steel structures.
* In
analytic number theory
In mathematics, analytic number theory is a branch of number theory that uses methods from mathematical analysis to solve problems about the integers. It is often said to have begun with Peter Gustav Lejeune Dirichlet's 1837 introduction of Dir ...
, chi is used for the
Dirichlet character
In analytic number theory and related branches of mathematics, a complex-valued arithmetic function \chi: \mathbb\rightarrow\mathbb is a Dirichlet character of modulus m (where m is a positive integer) if for all integers a and b:
# \chi(ab) = \ch ...
.
Unicode
*
[Unicode Code Charts]
Greek and Coptic (Range: 0370-03FF)
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See also
{{Wiktionary, Χ, χ
*Chi (disambiguation)
__NOTOC__
Chi may refer to:
__NOTOC__ Greek
*Chi (letter) (Χ or χ), the twenty-second letter of the Greek alphabet
Chinese
* ''Chi'' (length) (尺), a traditional unit of length, about ⅓ meter
* Chi (mythology) (螭), a dragon
* Chi (surname ...
* Х, х - Kha (Cyrillic)
References
Greek letters
Phonetic transcription symbols