# Zeta (ζήτα)
**Zeta** (ζήτα) is the sixth letter of the [Greek alphabet](https://www.edgepedia.org/greek-alphabet), written Ζ in uppercase and ζ in lowercase, and transliterated into the [Latin alphabet](https://www.edgepedia.org/latin-alphabet) as Z.[1](https://en.wiktionary.org/wiki/%CE%B6%CE%AE%CF%84%CE%B1) Its lowercase form is familiar in mathematics chiefly through the [Riemann zeta function](https://www.edgepedia.org/riemann-zeta-function).[2](https://arxiv.org/abs/1203.4142)
| Key fact | Detail |
|---|---|
| Position and forms | Sixth letter of the Greek alphabet; uppercase Ζ, lowercase ζ; transliterated Z[1](https://en.wiktionary.org/wiki/%CE%B6%CE%AE%CF%84%CE%B1) |
| Origin | Came directly from the Semitic alphabet; corresponds to Phoenician Zain, the seventh Phoenician letter, with approximately the same form as the early Greek Ζ[3](https://www.greece.com/info/language/greek_alphabet/Zeta/) • [4](https://en.wikisource.org/wiki/Page%3AEB1911_-_Volume_01.djvu/768) |
| Pronunciation | Classical Greek [zd], later [zː] and [z]; modern Greek z as in zoo[5](https://www.fact-archive.com/encyclopedia/Greek_letters) • [6](https://www.theology.edu/greek/gk01.htm) |
| Numerical value | 7 in Greek isopsephy (Milesian notation)[7](https://musicalgematria.org/gematria/gabout-grc.php) |
| Mathematical use | The Riemann zeta function[2](https://arxiv.org/abs/1203.4142) |
| Encoding | Unicode U+0396 (Ζ, greek capital letter zeta); Beta Code Z in the Thesaurus Linguae Graecae[8](https://www.unicode.org/Public//UCD/latest/charts/nameslist/1d400/) • [9](https://stephanus.tlg.uci.edu/encoding.php) |
## Origin and history
The Greek alphabet was adapted from the [Phoenician alphabet](https://www.edgepedia.org/phoenician-alphabet), and zeta came directly from the Semitic letter stock.[3](https://www.greece.com/info/language/greek_alphabet/Zeta/) In the Phoenician alphabet the corresponding letter was Zain, the seventh letter, whose form closely resembled the early Greek Ζ and whose sound was a voiced s-sound.[4](https://en.wikisource.org/wiki/Page%3AEB1911_-_Volume_01.djvu/768) The Greek adaptation shifted the letter one position earlier in the sequence: zeta is the sixth letter of the Greek alphabet, while "z" is the last letter of the Latin alphabet.[1](https://en.wiktionary.org/wiki/%CE%B6%CE%AE%CF%84%CE%B1) • [10](https://greekdoc.github.io/lessons/lesson01.html)
In classical Greek the letter was pronounced [zd], a cluster that later developed to [zː] and then simply [z].[5](https://www.fact-archive.com/encyclopedia/Greek_letters) [Modern Greek](https://www.edgepedia.org/modern-greek) keeps the z sound, as in zoo.[6](https://www.theology.edu/greek/gk01.htm) Some modern transliteration guides also allow a /dz/ pronunciation when the letter falls in the middle of a word.[11](https://sundaymorninggreekblog.com/greek-alphabet-chart/)
## Numerical value
Like the other Greek letters, zeta served as a numeral in the Milesian system of isopsephy, where it represents the value 7.[7](https://musicalgematria.org/gematria/gabout-grc.php) The classical 24-letter alphabet was extended with three archaic letters, stigma, koppa, and sampi, to complete the numeral series to 27 letters.[12](https://onlinegematriacalculator.com/greek-isopsephy-chart/)
## Use in mathematics
Lowercase ζ is a working symbol in mathematics. Its most prominent role is the Riemann zeta function, a central object in the study of the Riemann zeta function and the related [Dirichlet eta function](https://www.edgepedia.org/dirichlet-eta-function).[2](https://arxiv.org/abs/1203.4142) Like any Greek letter, ζ can also serve as a plain variable whose meaning depends on context.
## Computing and encoding
In Unicode, the uppercase letter is encoded at U+0396 as GREEK CAPITAL LETTER ZETA, with the lowercase ζ in the Greek block.[8](https://www.unicode.org/Public//UCD/latest/charts/nameslist/1d400/) The Thesaurus Linguae Graecae Beta Code, a legacy ASCII encoding for Greek texts, represents zeta with the Latin letter Z, capitalized as *Z for the uppercase form.[9](https://stephanus.tlg.uci.edu/encoding.php) In LaTeX the lowercase letter is produced by \zeta; the unicode-math package additionally distinguishes an upright mathematical variant, \mupzeta, from the default italic form.[13](https://typeanykey.com/guides/zeta)
## References
1. [ζήτα, Wiktionary](https://en.wiktionary.org/wiki/%CE%B6%CE%AE%CF%84%CE%B1)
2. [On accuracy of mathematical languages used to deal with the Riemann zeta function and the Dirichlet eta function, arXiv](https://arxiv.org/abs/1203.4142)
3. [Greek Letter Zeta (Ζήτα - Ζ), Greece.com](https://www.greece.com/info/language/greek_alphabet/Zeta/)
4. [Page:EB1911 - Volume 01.djvu/768, Wikisource](https://en.wikisource.org/wiki/Page%3AEB1911_-_Volume_01.djvu/768)
5. [Online dictionary - Greek alphabet, Fact Archive](https://www.fact-archive.com/encyclopedia/Greek_letters)
6. [Lesson 1: Koine Greek, theology.edu](https://www.theology.edu/greek/gk01.htm)
7. [Musical Gematria - Greek Isopsephy](https://musicalgematria.org/gematria/gabout-grc.php)
8. [Mathematical Alphanumeric Symbols / Greek names list, Unicode](https://www.unicode.org/Public//UCD/latest/charts/nameslist/1d400/)
9. [The Beta Code Manual, Thesaurus Linguae Graecae](https://stephanus.tlg.uci.edu/encoding.php)
10. [Lesson 1: Koine Greek, greekdoc.github.io](https://greekdoc.github.io/lessons/lesson01.html)
11. [Greek Alphabet Chart, Sunday Morning Greek Blog](https://sundaymorninggreekblog.com/greek-alphabet-chart/)
12. [Greek Isopsephy Chart, Online Gematria Calculator](https://onlinegematriacalculator.com/greek-isopsephy-chart/)
13. [Symbol zeta: How to Type Zeta (ζ), TypeAnyKey](https://typeanykey.com/guides/zeta)
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*Topic: Encyclopedia › Society and history › Languages and linguistics › Writing and notation systems › Mediterranean, Italic, and undeciphered ancient scripts*
*Initially written Sep 17, 2026 · Reviewed: Sep 18, 2026; Oct 25, 2026 · Edited: Sep 18, 2026; Oct 25, 2026 · Last review: Oct 25, 2026*
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License: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license