View source for Nu (letter)

{{Short description|Thirteenth letter in the Greek alphabet}}
{{Other uses|Nu (disambiguation)}}
{{Dist|Mu (letter)|N|En (Cyrillic)|Ͷ (disambiguation){{!}}Ͷ (Greek)|И (Cyrillic)|v}}
{{Greek Alphabet|letter=nu}}
'''Nu''' ({{IPAc-en|'|nj|uː|audio=LL-Q1860 (eng)-Flame, not lame-Nu.wav}}; uppercase '''Ν''', lowercase '''ν'''; {{langx|el|vι}} {{transliteration|el|ni}}, {{IPA|el|ni|}}) is the thirteenth letter of the [[Greek alphabet]], representing the [[voiced alveolar nasal]] {{IPA|el|n|}}. In the system of [[Greek numerals]] it has a value of 50. It is derived from the [[Phoenician alphabet|Phoenician]] [[Nun (letter)|nun]] [[Image:Phoenician nun.svg|20px]]. Its [[Latin script|Latin]] equivalent is [[N]], though the lowercase (<math>\nu</math>) resembles the Roman lowercase [[v]].

The name of the letter is {{lang|grc|νῦ}} ({{transliteration|grc|nû}}, {{IPA|grc|nŷː|}}) in [[Ancient Greek]], while in [[Modern Greek]] it is {{lang|el|νι|}} ({{transliteration|el|ni}}, {{IPA|el|ni|}}).

[[Letter (alphabet)|Letters]] that arose from nu include N in the [[Latin script]] and [[En (Cyrillic)|En]] (Н) in [[Cyrillic]].

==Symbology==
[[File:Nikos_Kazantzakis_Statue_in_Heraklion.jpg|thumb|upright=.95|Bust of [[Nikos Kazantzakis]] with the traditional Greek nu]]
The lower-case letter {{mvar|ν}} is used as a symbol in many [[academic field]]s. Uppercase nu is not used, because it appears identical to Latin [[N]].

* Mathematics:
** [[Degrees of freedom (statistics)|Degrees of freedom]] in [[statistics]].
** The [[greatest fixed point]] of a function, as commonly used in the [[μ-calculus]].
** Free names of a process, as used in the [[π-calculus#Syntax|π-calculus]].
** One of [[Greeks (finance)|the Greeks]] in [[mathematical finance]], known as "vega".
** The reciprocal of 1 plus the interest rate in finance.
** The [[p-adic valuation|{{mvar|p}}-adic valuation or {{mvar|p}}-adic order]] of a number.
*Physics:
** [[Viscosity#Kinematic viscosity|Kinematic viscosity]] in [[fluid mechanics]].<ref>{{Citation |last=Elert |first=Glenn |title=Special Symbols |date=2023 |work=The Physics Hypertextbook |url=https://physics.info/symbols/ |access-date=2025-02-01 |publisher=hypertextbook|quote= ν kinematic viscosity |language=en}}</ref>
** The [[frequency]]<ref>See e.g. [[Planck constant|Planck's formula]]</ref> of a wave in physics and other fields; sometimes also [[spatial frequency]]; [[wavenumber]]
** The [[specific volume]] in [[thermodynamics]].
** [[Poisson's ratio]], the ratio of strains perpendicular with and parallel with an applied force.
** Any of three kinds of [[neutrino]] in particle physics.
** The number of [[neutrons]] released per [[nuclear fission|fission]] of an atom in nuclear physics.
** Molecular [[vibrational mode]], {{math|''ν''<sub>''x''</sub>}} where {{mvar|x}} is the number of the vibration (a label).
** The [[true anomaly]], an angular parameter that defines the position of a body moving along an orbit (see [[orbital elements]]).
*Biology:
** [[DNA polymerase nu|A DNA polymerase]] found in higher [[eukaryotes]] and implicated in [[translesion synthesis]].
*Chemistry:
** The [[stoichiometric coefficient]].
*Psychology:
** The maximum conditioning possible for an [[unconditioned stimulus]] in the [[Rescorla-Wagner model]].

==Unicode==

Encodings of Greek Nu and Coptic Ni.<ref>Unicode Code Charts: [https://www.unicode.org/charts/PDF/U0370.pdf Greek and Coptic (Range: 0370-03FF)]</ref>

* {{unichar|039D|html=}}
* {{unichar|03BD|html=}} ({{code|\nu}} in [[TeX]])
* {{unichar|2C9A}}
* {{unichar|2C9B}}
* {{unichar|1D6B4}}{{efn|The {{sc|mathematical}} symbols should only be use for math. Stylized Greek text should be encoded using the normal Greek letters, with markup and formatting to indicate text style.}}
* {{unichar|1D6CE}}
* {{unichar|1D6EE}}
* {{unichar|1D708}}
* {{unichar|1D728}}
* {{unichar|1D742}}
* {{unichar|1D762}}
* {{unichar|1D77C}}
* {{unichar|1D79C}}
* {{unichar|1D7B6}}
{{notelist}}

== See also ==
{{Wiktionary|Ν|ν}}
* [[Movable nu]]
{{clear}}

==References==
{{Reflist}}

{{Authority control}}

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[[Category:Greek letters]]