imported>UnbihexiumFan: /* Symbol */ Denticity is marked by lowercase kappa

2025-10-10T22:29:29Z

Symbol: Denticity is marked by lowercase kappa

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{{short description|Tenth letter in the Greek Alphabet}}
{{Other uses}}{{Distinguish}}{{About|the Greek letter|the archaic Greek letter with a similar name|Koppa (letter)}}{{Distinguish|text=the similar looking Cyrillic letter [[Ka (Cyrillic)|Ka]]}}
{{Greek Alphabet|letter=kappa}}
[[File:Greek lowercase kappa variant.svg|thumb|right|75px|Variant kappa]]
[[File:Greek word καί written with a handwritten variant of kappa, from the Byzantine period.png|thumb|right|Greek word καί written with a handwritten variant of kappa, from the Byzantine period]]
'''Kappa''' ({{IPAc-en|'|k|æ|p|ə|audio=LL-Q1860 (eng)-Flame, not lame-Kappa.wav}};<ref>{{OED|kappa}}</ref> uppercase '''Κ''', lowercase '''κ''' or [[Cursive Greek|cursive]] {{not a typo|'''ϰ'''}}; {{langx|el|κάππα}}, ''káppa'') is the tenth letter of the [[Greek alphabet]], representing the [[voiceless velar plosive]] {{IPA|el|k|IPA}} sound in [[Ancient Greek|Ancient]] and [[Modern Greek]]. In the system of [[Greek numerals]], {{lang|el|Kʹ}} has a value of 20. It was derived from the Phoenician letter [[kaph]] <span style="background-color: white;">[[Image:Phoenician kaph.svg|20px]]</span>. Letters that arose from kappa include the Roman [[K]] and Cyrillic [[Ka (Cyrillic)|К]]. The uppercase form is identical to the Latin K.

Greek proper names and placenames containing kappa are often written in English with "c" due to the [[Ancient Rome|Roman]]s' [[Romanization of Greek#Ancient Greek|transliteration]]s into the [[Latin alphabet]]: [[Constantinople]], [[Corinth]], [[Crete]]. [[Romanization of Greek|All formal modern romanizations]] of Greek now use the letter "k", however.{{citation needed|date=February 2018}}

{{anchor|Cursive kappa|{{not a typo|ϰ}}}}
The [[Greek cursive|cursive]] form {{lang|grc|{{not a typo|ϰ}}}} is generally a simple font variant of lower-case kappa, but it is encoded separately in [[Unicode]] for occasions where it is used as a separate symbol in math and science. In [[mathematics]], the [[kappa curve]] is named after this letter; the [[tangent]]s of this [[curve]] were first calculated by [[Isaac Barrow]] in the 17th century.

==Symbol==
===Lowercase (κ)===
;Mathematics and statistics
* In [[graph theory]], the [[connectivity (graph theory)|connectivity]] of a [[Graph (discrete mathematics)|graph]] is given by ''κ''.<ref>{{Cite web |last=Weisstein |first=Eric W. |title=Vertex Connectivity |url=https://mathworld.wolfram.com/VertexConnectivity.html |access-date=2025-02-05 |website=mathworld.wolfram.com |language=en}}</ref>
* In [[differential geometry]], the [[curvature]] of a curve is given by ''κ''.<ref>{{Cite web |last=Weisstein |first=Eric W. |title=Curvature |url=https://mathworld.wolfram.com/Curvature.html |access-date=2025-02-05 |website=mathworld.wolfram.com |language=en |quote=Then the curvature κ, sometimes also called the "first curvature" (Kreyszig 1991, p. 47), is defined by...}}</ref>
* In [[linear algebra]], the [[condition number]] of a matrix is given by ''κ''.<ref>{{Cite web |title=DLMF: §3.2 Linear Algebra ‣ Areas ‣ Chapter 3 Numerical Methods |url=https://dlmf.nist.gov/3.2#v.p1 |access-date=2025-01-31 |website=dlmf.nist.gov}}</ref>
* The [[kappa curve]], also known as Gutschoven's curve, is a curve whose shape resembles the letter ''κ.''<ref>{{Cite web |last=Weisstein |first=Eric W. |title=Kappa Curve |url=https://mathworld.wolfram.com/KappaCurve.html |access-date=2025-02-05 |website=mathworld.wolfram.com |language=en}}</ref>
* Kappa statistics such as [[Cohen's kappa]]<ref name="Mary2012">{{cite journal|last1=McHugh|first1=Mary L.|year=2012|title=Interrater reliability: The kappa statistic|journal=Biochemia Medica|volume=22|issue=3|pages=276–282|doi=10.11613/bm.2012.031|pmc=3900052|pmid=23092060}}</ref><ref>{{Cite book |last=Gwet |first=Kilem Li |title=Handbook of inter-rater reliability: the definitive guide to measuring the extent of agreement among raters |date=2014 |publisher=Advances Analytics, LLC |isbn=978-0-9708062-8-4 |edition=Fourth |location=Gaithersburg, Md |pages=32 |quote=Cohen's Kappa Definition}}</ref> and [[Fleiss' kappa]] are methods for calculating [[inter-rater reliability]].

;Physics
* In [[cosmology]], the [[Einstein gravitational constant]] is denoted by ''κ''.<ref>{{Cite book |last=Carmeli |first=Moshe |title=Classical fields: general relativity and gauge theory |date=1982 |publisher=J. Wiley |isbn=978-0-471-86437-0 |location=New York |pages=85 |quote=Here ''κ'' is some constant called ''Einstein's gravitational constant''.}}</ref>
* In [[physics]], the [[torsion spring|torsional constant]] of an [[oscillation|oscillator]] is given by ''κ''.<ref>{{Cite book |last=Halliday |first=David |title=Principles of physics |last2=Resnick |first2=Robert |last3=Walker |first3=Jearl |date=2023 |publisher=Wiley |isbn=978-1-119-82061-1 |edition=Twelfth |series=International adaptation |location=Singapore |pages=447 |quote=Here ''κ'' (Greek ''kappa'') is a constant, called the '''torsion constant''',}}</ref>
* In physics, the coupling coefficient in magnetostatics is represented by ''κ''.<ref>{{Cite book |last=Stancil |first=Daniel D. |title=Theory of magnetostatic waves |date=1993 |publisher=Springer-Verlag |isbn=978-0-387-97969-4 |location=New York |pages=200 |quote=The coupling coefficient (7.136) can now be written ''κ''{{sub|ab}} =...}}</ref>
* In physics, the dielectric coefficient is represented by ''κ''.
* In [[fluid dynamics]], the [[von Kármán constant]] is represented by ''κ''.<ref>{{Cite journal |last=Monkewitz |first=Peter A. |last2=Nagib |first2=Hassan M. |date=2023 |title=The hunt for the Kármán 'constant' revisited |url=https://www.cambridge.org/core/journals/journal-of-fluid-mechanics/article/hunt-for-the-karman-constant-revisited/F9DA84F93A1E268BFC5F9E1CB5622E5E |journal=Journal of Fluid Mechanics |language=en |volume=967 |pages=A15 |doi=10.1017/jfm.2023.448 |issn=0022-1120|arxiv=2303.08071 }}</ref>
* [[thermal conductivity]]<ref>{{Cite web |title=Thermal Conductivity - Definition and Detailed Explanation |url=https://byjus.com/chemistry/thermal-conductivity/ |access-date=2025-02-05 |website=BYJUS |language=en |quote=It is generally denoted by the symbol 'k' but can also be denoted by 'λ' and 'κ'.}}</ref>
* In [[thermodynamics]], the [[compressibility]] of a compound is given by ''κ''.<ref>{{Cite book |title=Transition metal and rare earth compounds. 3 |date=2004 |publisher=Springer |isbn=978-3-540-20948-5 |series=Topics in current chemistry |location=Berlin Heidelberg |pages=5 |quote=The isothermal compressibility, ''κ'' ...}}</ref>

;Engineering
* In [[structural engineering]], ''κ'' is the ratio of the smaller factored moment to the larger factored moment and is used to calculate the critical [[elastic moment]] of an unbraced steel member.
* In [[electrical engineering]], ''κ'' is the multiplication factor, a function of the ''R''/''X'' ratio of the equivalent power system network, which is used in calculating the peak short-circuit current of a system fault. ''κ'' is also used to denote conductivity, the reciprocal of resistivity, [[rho]].

;Biology and biomedical science
* In [[biology]], kappa and kappa prime are important [[nucleotide]] motifs for a tertiary interaction of [[group II intron]]s.
* In [[biology]], kappa designates a subtype of an [[antibody]] component.
* In [[pharmacology]], kappa represents a type of [[opioid receptor]].<ref>{{Cite book |title=Opioids and Their Receptors: Present and Emerging Concepts in Opioid Drug Discovery II |date=2022 |publisher=MDPI - Multidisciplinary Digital Publishing Institute |isbn=978-3-0365-4352-9 |editor-last=Spetea |editor-first=Mariana |location=Basel |quote=From a chemical standpoint, opioids comprise a diverse group of drugs, but they all share a common affinity towards μ,δ, and κ receptors |editor-last2=van Rijn |editor-first2=Richard M.}}</ref>

;Psychology and psychiatry
* In [[psychology]] and [[psychiatry]], kappa represents a measure of diagnostic reliability.<ref>{{Cite book |last=Sadler |first=John Z. |title=Values and psychiatric diagnosis |date=2005 |publisher=Oxford University Press |isbn=978-0-19-852637-7 |series=International perspectives in philosophy and psychiatry |location=Oxford New York, NY |pages=118 |quote=...the other (4b) involve the new (to psychiatry) use of the kappa statistic as a means of measuring diagnostic reliability.}}</ref>

;Economics
* In [[macroeconomics]], kappa represents the capital-utilization rate.<ref>{{Cite web|title=University of Hong Kong School of Business|url=http://www.sef.hku.hk/tpg/econ6022b/lecture_note_6_revised.pdf|website=HKU}}</ref>

;Chemistry

* In [[chemistry]], kappa is used to denote the [[denticity]] of the compound.<ref>{{Cite book |last=Strohfeldt |first=Katja A. |title=Essentials of Inorganic Chemistry: For Students of Pharmacy, Pharmaceutical Sciences and Medicinal Chemistry |date=2015 |publisher=John Wiley & Sons, Incorporated |isbn=978-0-470-66558-9 |location=Newark |pages=251 |quote=In terms of the nomenclature, the denticity of the ligand is denoted by the Greek letter κ (kappa)}}</ref>

===Uppercase (Κ)===
;History
* In [[textual criticism]], the [[Byzantine text-type]] (from Κοινη, ''Koine'', the common text).

;Mathematics and statistics
* In [[set theory]], kappa is often used to denote an [[ordinal number|ordinal]] that is also a [[cardinal number|cardinal]].

;Chemistry
* In [[Pulp (paper)|pulping]], the [[kappa number]] represents the amount of an oxidizing agent required for bleaching a pulp.

==Unicode==

* {{unichar|039A|html=}}
* {{unichar|03BA|html=}}
* {{unichar|03F0|html=}}
* {{unichar|2C94|html=}}
* {{unichar|2C95|html=}}
* {{unichar|2CB8|html=}}
* {{unichar|2CB9|html=}}
* {{unichar|1D6B1|html=}}{{efn|The {{sc|mathematical}} symbols are only used for math. Stylized Greek text should be encoded using the normal Greek letters, with markup and formatting to indicate text style.}}
* {{unichar|1D6CB|html=}}
* {{unichar|1D6DE|html=}}
* {{unichar|1D6EB|html=}}
* {{unichar|1D705|html=}}
* {{unichar|1D718|html=}}
* {{unichar|1D725|html=}}
* {{unichar|1D73F|html=}}
* {{unichar|1D752|html=}}
* {{unichar|1D75F|html=}}
* {{unichar|1D779|html=}}
* {{unichar|1D78C|html=}}
* {{unichar|1D799|html=}}
* {{unichar|1D7B3|html=}}
* {{unichar|1D7C6|html=}}
{{notelist}}

{{commons category|Kappa (letter)}}{{wiktionary|Κ|κ}}

==References==
{{reflist}}

[[Category:Greek letters]]

Kappa - Revision history

imported>UnbihexiumFan: /* Symbol */ Denticity is marked by lowercase kappa