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Gamma (uppercase , lowercase ; ''gámma'') is the third letter of the
Greek alphabet The Greek alphabet has been used to write the Greek language since the late ninth or early eighth century BC. It is derived from the earlier Phoenician alphabet, and was the first alphabetic script in history to have distinct letters for vowels ...
. In the system of
Greek numerals Greek numerals, also known as Ionic, Ionian, Milesian, or Alexandrian numerals, are 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), ordina ...
it has a value of 3. 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 (), Dark Ages () ...
, the letter gamma represented a voiced velar stop . 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 l ...
, this letter represents either a voiced velar fricative or a
voiced palatal fricative The voiced palatal fricative is a type of consonant In articulatory phonetics, a consonant is a speech sound that is articulated with complete or partial closure of the vocal tract. Examples are , pronounced with the lips; , pronounced with the ...
. In the
International Phonetic Alphabet The International Phonetic Alphabet (IPA) is an alphabetic system of phonetic notation based primarily on the Latin script Latin script, also known as Roman script, is a set of graphic signs (Writing system#General properties, script) b ...
and other modern Latin-alphabet based phonetic notations, it represents the voiced velar fricative.

# History

The Greek letter Gamma Γ was derived from the for the /g/ phoneme ( ''gīml''), and as such is cognate with
Hebrew Hebrew (, , or ) is a Northwest Semitic languages, Northwest Semitic language of the Afroasiatic languages, Afroasiatic language family. Historically, it is regarded as the language of the Israelites, Judeans and their ancestors. It is the o ...
''
gimel Gimel is the third letter of the Semitic abjads, including Phoenician Gīml , Hebrew Hebrew (, , or ) is a Northwest Semitic languages, Northwest Semitic language of the Afroasiatic languages, Afroasiatic language family. Historically, ...

'' ג. Based on its name, the letter has been interpreted as an abstract representation of a
camel A camel is an even-toed ungulate in the genus ''Camelus'' that bears distinctive fatty deposits known as "humps" on its back. Camels have long been domesticated and, as livestock, they provide food (milk Milk is a nutrient-rich liquid ...
's neck, but this has been criticized as contrived, and it is more likely that the letter is derived from an Egyptian hieroglyph representing a club or
throwing stick 240px, Hunting birds with throwing sticks in ancient Egypt The throwing stick or throwing club is a wooden rod with either a pointed tip or a spearhead attached to one end, intended for use as a weapon. A throwing stick can be either straight or ...
. In
Archaic Greece Archaic Greece was the period in Greek history lasting from the eighth century BC to the second Persian invasion of Greece The second Achaemenid Empire, Persian invasion of Ancient Greece, Greece (480–479 BC) occurred during the Greco-Pers ...
, the shape of gamma was closer to a classical
lambda Lambda (; uppercase , lowercase ; el, λάμ(β)δα, ''lám(b)da'') is the 11th letter of the Greek alphabet The Greek alphabet has been used to write the Greek language since the late ninth or early eighth century BC. It is derived from ...
(Λ), while lambda retained the Phoenician L-shape (). Letters that arose from the Greek gamma include Etruscan (Old Italic) 𐌂, Roman C and G, Elder Futhark, Runic ''kaunan'' , Gothic alphabet, Gothic ''geuua'' , the Coptic alphabet, Coptic Ⲅ, and the Cyrillic script, Cyrillic letters Ge (Cyrillic), Г and Ge with upturn, Ґ.

# Greek phoneme

The Ancient Greek /g/ phoneme was the voiced velar stop, continuing the reconstructed Proto-Indo-European phonology, proto-Indo-European ''*g'', ''*ǵ''. The modern Greek phoneme represented by gamma is realized either as a voiced palatal fricative () before a front vowel (/e/, /i/), or as a voiced velar fricative in all other environments. Both in Ancient and in Modern Greek, before other velar consonants (κ, χ, ξ ''k, kh, ks''), gamma represents a velar nasal . A double gamma γγ represents the sequence (phonetically varying ) or .

# Phonetic transcription

Lowercase Greek gamma is used in the Americanist phonetic notation and Uralic Phonetic Alphabet to indicate voiced consonants. The gamma was also added to the Latin alphabet, as Latin gamma, in the following forms: majuscule Ɣ, minuscule ɣ, and superscript modifier letter ˠ. In the
International Phonetic Alphabet The International Phonetic Alphabet (IPA) is an alphabetic system of phonetic notation based primarily on the Latin script Latin script, also known as Roman script, is a set of graphic signs (Writing system#General properties, script) b ...
the minuscule letter is used to represent a voiced velar fricative and the superscript modifier letter is used to represent velarization. It is not to be confused with the character , which looks like a lowercase Latin gamma that lies above the baseline (typography), baseline rather than crossing, and which represents the close-mid back unrounded vowel. In certain Obsolete and nonstandard symbols in the International Phonetic Alphabet, nonstandard variations of the IPA, the uppercase form is used. It is as a full-fledged majuscule and minuscule letter in the alphabets of some of languages of Africa such as Dagbani language, Dagbani, Dinka language, Dinka, Kabye language, Kabye, and Ewe language, Ewe, and Berber languages using the Berber Latin alphabet. It is sometimes also used in the romanization of Pashto.

# Mathematics and science

## Lowercase

The lowercase letter $\gamma$ is used as a symbol for: *Chromatic number of in graph theory *Gamma ray, Gamma radiation in nuclear physics *The photon, the elementary particle of light and other electromagnetic radiation *Surface energy in materials science *The Lorentz factor in the theory of relativity *In mathematics, the Incomplete gamma function, lower incomplete gamma function *The heat capacity ratio Cp/Cv in thermodynamics *The activity coefficient in thermodynamics *The gyromagnetic ratio in electromagnetism *Gamma waves in neuroscience *Gamma motor neurons in neuroscience *A non-International System of Units, SI metric system, metric units of measurement, unit of measure of mass equal to one microgram (1 μg).François Cardarelli (2003). Encyclopaedia of Scientific Units, Weights and Measures. Springer-Verlag London Ltd. . This always-rare use is currently deprecated. *A non-International System of Units, SI units of measurement, unit of measure of magnetic field, magnetic flux density, sometimes used in geophysics, equal to 1 nano-, nanotesla (unit), tesla (nT). *The power by which the luminance of an image is increased in gamma correction *The Euler–Mascheroni constant *In civil and mechanical engineering: **Specific weight **The shear rate of a fluid is represented by a lowercase gamma with a dot above it: $\dot \gamma$ **Austenite (also known as γ-iron), a metallic non-magnetic allotrope or solid solution of iron. *The gamma carbon, the third carbon attached to a functional group in organic chemistry and biochemistry; see Alpha and beta carbon The lowercase Latin gamma ɣ can also be used in contexts (such as chemical or molecule nomenclature) where gamma must not be confused with the letter y, which can occur in some computer typefaces.

## Uppercase

The uppercase letter $\Gamma$ is used as a symbol for: *In mathematics, the gamma function (usually written as $\Gamma$-function) is an extension of the factorial to complex numbers *In mathematics, the Incomplete gamma function, upper incomplete gamma function *The Christoffel symbols in differential geometry *In probability theory and statistics, the gamma distribution is a two-parameter family of continuous probability distributions. *In solid-state physics, the center of the Brillouin zone *circulation (fluid dynamics), Circulation in fluid mechanics *As reflection coefficient in physics and electrical engineering *The tape alphabet of a Turing machine *The Feferman–Schütte ordinal $\Gamma_0$ *One of the Greeks (finance), Greeks in mathematical finance

# Encoding

## HTML

The List of XML and HTML character entity references#Character entity references in HTML, HTML entities for uppercase and lowercase gamma are &Gamma; and &gamma;.

## Unicode

* Greek Gamma * Coptic Gamma * Latin Gamma / International Phonetic Alphabet, phonetic Gamma * CJK Square Gamma * Technical / Mathematical Gamma 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.