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id="toc-Pure_mathematics" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Pure_mathematics"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.1.1</span> <span>Pure mathematics</span> </div> </a> <ul id="toc-Pure_mathematics-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Physics" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Physics"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.1.2</span> <span>Physics</span> </div> </a> <ul id="toc-Physics-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Other_uses" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Other_uses"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.1.3</span> <span>Other uses</span> </div> </a> <ul id="toc-Other_uses-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Lowercase" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Lowercase"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.2</span> <span>Lowercase</span> </div> </a> <ul id="toc-Lowercase-sublist" class="vector-toc-list"> <li id="toc-Pure_mathematics_2" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Pure_mathematics_2"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.2.1</span> <span>Pure mathematics</span> </div> </a> <ul id="toc-Pure_mathematics_2-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Physics_and_astronomy" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Physics_and_astronomy"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.2.2</span> <span>Physics and astronomy</span> </div> </a> <ul id="toc-Physics_and_astronomy-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Other_uses_2" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Other_uses_2"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.2.3</span> <span>Other uses</span> </div> </a> <ul id="toc-Other_uses_2-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> </ul> </li> <li id="toc-Other_uses_3" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Other_uses_3"> <div class="vector-toc-text"> <span class="vector-toc-numb">4</span> <span>Other uses</span> </div> </a> <ul id="toc-Other_uses_3-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Unicode" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Unicode"> <div class="vector-toc-text"> <span class="vector-toc-numb">5</span> <span>Unicode</span> </div> </a> <ul id="toc-Unicode-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-References" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#References"> <div class="vector-toc-text"> <span class="vector-toc-numb">6</span> <span>References</span> </div> </a> <ul id="toc-References-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-External_links" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#External_links"> <div class="vector-toc-text"> <span class="vector-toc-numb">7</span> <span>External links</span> </div> </a> <ul id="toc-External_links-sublist" class="vector-toc-list"> </ul> </li> </ul> </div> </div> </nav> </div> </div> <div class="mw-content-container"> <main id="content" class="mw-body"> <header class="mw-body-header vector-page-titlebar"> <nav aria-label="Contents" class="vector-toc-landmark"> <div id="vector-page-titlebar-toc" class="vector-dropdown vector-page-titlebar-toc vector-button-flush-left" > <input type="checkbox" id="vector-page-titlebar-toc-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-page-titlebar-toc" class="vector-dropdown-checkbox " aria-label="Toggle the table of contents" > <label id="vector-page-titlebar-toc-label" for="vector-page-titlebar-toc-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only " aria-hidden="true" ><span class="vector-icon mw-ui-icon-listBullet mw-ui-icon-wikimedia-listBullet"></span> <span class="vector-dropdown-label-text">Toggle the table of contents</span> </label> <div class="vector-dropdown-content"> <div id="vector-page-titlebar-toc-unpinned-container" class="vector-unpinned-container"> </div> </div> </div> </nav> <h1 id="firstHeading" class="firstHeading mw-first-heading"><span class="mw-page-title-main">Xi (letter)</span></h1> <div id="p-lang-btn" class="vector-dropdown mw-portlet mw-portlet-lang" > <input type="checkbox" id="p-lang-btn-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-p-lang-btn" class="vector-dropdown-checkbox mw-interlanguage-selector" aria-label="Go to an article in another language. Available in 82 languages" > <label id="p-lang-btn-label" for="p-lang-btn-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--action-progressive mw-portlet-lang-heading-82" aria-hidden="true" ><span class="vector-icon mw-ui-icon-language-progressive mw-ui-icon-wikimedia-language-progressive"></span> <span class="vector-dropdown-label-text">82 languages</span> </label> <div class="vector-dropdown-content"> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="interlanguage-link interwiki-af mw-list-item"><a href="https://af.wikipedia.org/wiki/Ksi" title="Ksi – Afrikaans" lang="af" hreflang="af" data-title="Ksi" data-language-autonym="Afrikaans" data-language-local-name="Afrikaans" class="interlanguage-link-target"><span>Afrikaans</span></a></li><li class="interlanguage-link interwiki-als mw-list-item"><a href="https://als.wikipedia.org/wiki/%CE%9E" title="Ξ – Alemannic" lang="gsw" hreflang="gsw" data-title="Ξ" data-language-autonym="Alemannisch" data-language-local-name="Alemannic" class="interlanguage-link-target"><span>Alemannisch</span></a></li><li class="interlanguage-link interwiki-ab mw-list-item"><a href="https://ab.wikipedia.org/wiki/%CE%9E" title="Ξ – Abkhazian" lang="ab" hreflang="ab" data-title="Ξ" data-language-autonym="Аԥсшәа" data-language-local-name="Abkhazian" class="interlanguage-link-target"><span>Аԥсшәа</span></a></li><li class="interlanguage-link interwiki-ar mw-list-item"><a href="https://ar.wikipedia.org/wiki/%D9%83%D8%B3%D9%8A_(%D8%AD%D8%B1%D9%81)" title="كسي (حرف) – Arabic" lang="ar" hreflang="ar" data-title="كسي (حرف)" data-language-autonym="العربية" data-language-local-name="Arabic" class="interlanguage-link-target"><span>العربية</span></a></li><li class="interlanguage-link interwiki-arc mw-list-item"><a href="https://arc.wikipedia.org/wiki/%CE%9E" title="Ξ – Aramaic" lang="arc" hreflang="arc" data-title="Ξ" data-language-autonym="ܐܪܡܝܐ" data-language-local-name="Aramaic" class="interlanguage-link-target"><span>ܐܪܡܝܐ</span></a></li><li class="interlanguage-link interwiki-bn mw-list-item"><a href="https://bn.wikipedia.org/wiki/%E0%A6%B8%E0%A6%BF_(%E0%A6%97%E0%A7%8D%E0%A6%B0%E0%A6%BF%E0%A6%95_%E0%A6%AC%E0%A6%B0%E0%A7%8D%E0%A6%A3)" title="সি (গ্রিক বর্ণ) – Bangla" lang="bn" hreflang="bn" data-title="সি (গ্রিক বর্ণ)" data-language-autonym="বাংলা" data-language-local-name="Bangla" class="interlanguage-link-target"><span>বাংলা</span></a></li><li class="interlanguage-link interwiki-zh-min-nan mw-list-item"><a href="https://zh-min-nan.wikipedia.org/wiki/%CE%9E" title="Ξ – Minnan" lang="nan" hreflang="nan" data-title="Ξ" data-language-autonym="閩南語 / Bân-lâm-gú" data-language-local-name="Minnan" class="interlanguage-link-target"><span>閩南語 / Bân-lâm-gú</span></a></li><li class="interlanguage-link interwiki-be mw-list-item"><a href="https://be.wikipedia.org/wiki/%D0%9A%D1%81%D1%96_(%D0%BB%D1%96%D1%82%D0%B0%D1%80%D0%B0)" title="Ксі (літара) – Belarusian" lang="be" hreflang="be" data-title="Ксі (літара)" data-language-autonym="Беларуская" data-language-local-name="Belarusian" class="interlanguage-link-target"><span>Беларуская</span></a></li><li class="interlanguage-link interwiki-be-x-old mw-list-item"><a href="https://be-tarask.wikipedia.org/wiki/%D0%9A%D1%81%D1%96_(%D0%B3%D1%80%D1%8D%D1%86%D0%BA%D0%B0%D1%8F_%D0%BB%D1%96%D1%82%D0%B0%D1%80%D0%B0)" title="Ксі (грэцкая літара) – Belarusian (Taraškievica orthography)" lang="be-tarask" hreflang="be-tarask" data-title="Ксі (грэцкая літара)" data-language-autonym="Беларуская (тарашкевіца)" data-language-local-name="Belarusian (Taraškievica orthography)" class="interlanguage-link-target"><span>Беларуская (тарашкевіца)</span></a></li><li class="interlanguage-link interwiki-bg mw-list-item"><a href="https://bg.wikipedia.org/wiki/%D0%9A%D1%81%D0%B8" title="Кси – Bulgarian" lang="bg" hreflang="bg" data-title="Кси" data-language-autonym="Български" data-language-local-name="Bulgarian" class="interlanguage-link-target"><span>Български</span></a></li><li class="interlanguage-link interwiki-bar mw-list-item"><a href="https://bar.wikipedia.org/wiki/Xi" title="Xi – Bavarian" lang="bar" hreflang="bar" data-title="Xi" data-language-autonym="Boarisch" data-language-local-name="Bavarian" class="interlanguage-link-target"><span>Boarisch</span></a></li><li class="interlanguage-link interwiki-bo mw-list-item"><a href="https://bo.wikipedia.org/wiki/%E0%BD%81%E0%BD%B2%E0%BC%8B%E0%BD%A6%E0%BD%A0%E0%BD%BA%E0%BC%8D" title="ཁི་སའེ། – Tibetan" lang="bo" hreflang="bo" data-title="ཁི་སའེ།" data-language-autonym="བོད་ཡིག" data-language-local-name="Tibetan" class="interlanguage-link-target"><span>བོད་ཡིག</span></a></li><li class="interlanguage-link interwiki-br mw-list-item"><a href="https://br.wikipedia.org/wiki/Xi_(lizherenn)" title="Xi (lizherenn) – Breton" lang="br" hreflang="br" data-title="Xi (lizherenn)" data-language-autonym="Brezhoneg" data-language-local-name="Breton" class="interlanguage-link-target"><span>Brezhoneg</span></a></li><li class="interlanguage-link interwiki-ca mw-list-item"><a href="https://ca.wikipedia.org/wiki/Ksi" title="Ksi – Catalan" lang="ca" hreflang="ca" data-title="Ksi" data-language-autonym="Català" data-language-local-name="Catalan" class="interlanguage-link-target"><span>Català</span></a></li><li class="interlanguage-link interwiki-cs mw-list-item"><a href="https://cs.wikipedia.org/wiki/Ks%C3%AD" title="Ksí – Czech" lang="cs" hreflang="cs" data-title="Ksí" data-language-autonym="Čeština" data-language-local-name="Czech" class="interlanguage-link-target"><span>Čeština</span></a></li><li class="interlanguage-link interwiki-cy mw-list-item"><a href="https://cy.wikipedia.org/wiki/Xi" title="Xi – Welsh" lang="cy" hreflang="cy" data-title="Xi" data-language-autonym="Cymraeg" data-language-local-name="Welsh" class="interlanguage-link-target"><span>Cymraeg</span></a></li><li class="interlanguage-link interwiki-da mw-list-item"><a href="https://da.wikipedia.org/wiki/Xi_(bogstav)" title="Xi (bogstav) – Danish" lang="da" hreflang="da" data-title="Xi (bogstav)" data-language-autonym="Dansk" data-language-local-name="Danish" class="interlanguage-link-target"><span>Dansk</span></a></li><li class="interlanguage-link interwiki-se mw-list-item"><a href="https://se.wikipedia.org/wiki/%CE%9E" title="Ξ – Northern Sami" lang="se" hreflang="se" data-title="Ξ" data-language-autonym="Davvisámegiella" data-language-local-name="Northern Sami" class="interlanguage-link-target"><span>Davvisámegiella</span></a></li><li class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/Xi" title="Xi – German" lang="de" hreflang="de" data-title="Xi" data-language-autonym="Deutsch" data-language-local-name="German" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-et mw-list-item"><a href="https://et.wikipedia.org/wiki/Ksii" title="Ksii – Estonian" lang="et" hreflang="et" data-title="Ksii" data-language-autonym="Eesti" data-language-local-name="Estonian" class="interlanguage-link-target"><span>Eesti</span></a></li><li class="interlanguage-link interwiki-el mw-list-item"><a href="https://el.wikipedia.org/wiki/%CE%9E%CE%B9" title="Ξι – Greek" lang="el" hreflang="el" data-title="Ξι" data-language-autonym="Ελληνικά" data-language-local-name="Greek" class="interlanguage-link-target"><span>Ελληνικά</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/%CE%9E" title="Ξ – Spanish" lang="es" hreflang="es" data-title="Ξ" data-language-autonym="Español" data-language-local-name="Spanish" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-eo mw-list-item"><a href="https://eo.wikipedia.org/wiki/Ksio" title="Ksio – Esperanto" lang="eo" hreflang="eo" data-title="Ksio" data-language-autonym="Esperanto" data-language-local-name="Esperanto" class="interlanguage-link-target"><span>Esperanto</span></a></li><li class="interlanguage-link interwiki-eu mw-list-item"><a href="https://eu.wikipedia.org/wiki/Xi" title="Xi – Basque" lang="eu" hreflang="eu" data-title="Xi" data-language-autonym="Euskara" data-language-local-name="Basque" class="interlanguage-link-target"><span>Euskara</span></a></li><li class="interlanguage-link interwiki-fa mw-list-item"><a href="https://fa.wikipedia.org/wiki/%DA%A9%D8%B3%DB%8C" title="کسی – Persian" lang="fa" hreflang="fa" data-title="کسی" data-language-autonym="فارسی" data-language-local-name="Persian" class="interlanguage-link-target"><span>فارسی</span></a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/Xi" title="Xi – French" lang="fr" hreflang="fr" data-title="Xi" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target"><span>Français</span></a></li><li class="interlanguage-link interwiki-ga mw-list-item"><a href="https://ga.wikipedia.org/wiki/X%C3%AD" title="Xí – Irish" lang="ga" hreflang="ga" data-title="Xí" data-language-autonym="Gaeilge" data-language-local-name="Irish" class="interlanguage-link-target"><span>Gaeilge</span></a></li><li class="interlanguage-link interwiki-gd mw-list-item"><a href="https://gd.wikipedia.org/wiki/Xi" title="Xi – Scottish Gaelic" lang="gd" hreflang="gd" data-title="Xi" data-language-autonym="Gàidhlig" data-language-local-name="Scottish Gaelic" class="interlanguage-link-target"><span>Gàidhlig</span></a></li><li class="interlanguage-link interwiki-gl mw-list-item"><a href="https://gl.wikipedia.org/wiki/Xi" title="Xi – Galician" lang="gl" hreflang="gl" data-title="Xi" data-language-autonym="Galego" data-language-local-name="Galician" class="interlanguage-link-target"><span>Galego</span></a></li><li class="interlanguage-link interwiki-hak mw-list-item"><a href="https://hak.wikipedia.org/wiki/%CE%9E" title="Ξ – Hakka Chinese" lang="hak" hreflang="hak" data-title="Ξ" data-language-autonym="客家語 / Hak-kâ-ngî" data-language-local-name="Hakka Chinese" class="interlanguage-link-target"><span>客家語 / Hak-kâ-ngî</span></a></li><li class="interlanguage-link interwiki-ko mw-list-item"><a href="https://ko.wikipedia.org/wiki/%CE%9E" title="Ξ – Korean" lang="ko" hreflang="ko" data-title="Ξ" data-language-autonym="한국어" data-language-local-name="Korean" class="interlanguage-link-target"><span>한국어</span></a></li><li class="interlanguage-link interwiki-hy mw-list-item"><a href="https://hy.wikipedia.org/wiki/%D5%94%D5%BD%D5%AB_(%D5%BF%D5%A1%D5%BC)" title="Քսի (տառ) – Armenian" lang="hy" hreflang="hy" data-title="Քսի (տառ)" data-language-autonym="Հայերեն" data-language-local-name="Armenian" class="interlanguage-link-target"><span>Հայերեն</span></a></li><li class="interlanguage-link interwiki-hr mw-list-item"><a href="https://hr.wikipedia.org/wiki/Ksi" title="Ksi – Croatian" lang="hr" hreflang="hr" data-title="Ksi" data-language-autonym="Hrvatski" data-language-local-name="Croatian" class="interlanguage-link-target"><span>Hrvatski</span></a></li><li class="interlanguage-link interwiki-id mw-list-item"><a href="https://id.wikipedia.org/wiki/Ksi_(huruf_Yunani)" title="Ksi (huruf Yunani) – Indonesian" lang="id" hreflang="id" data-title="Ksi (huruf Yunani)" data-language-autonym="Bahasa Indonesia" data-language-local-name="Indonesian" class="interlanguage-link-target"><span>Bahasa Indonesia</span></a></li><li class="interlanguage-link interwiki-is mw-list-item"><a href="https://is.wikipedia.org/wiki/X%C3%AD" title="Xí – Icelandic" lang="is" hreflang="is" data-title="Xí" data-language-autonym="Íslenska" data-language-local-name="Icelandic" class="interlanguage-link-target"><span>Íslenska</span></a></li><li class="interlanguage-link interwiki-it mw-list-item"><a href="https://it.wikipedia.org/wiki/Xi_(lettera)" title="Xi (lettera) – Italian" lang="it" hreflang="it" data-title="Xi (lettera)" data-language-autonym="Italiano" data-language-local-name="Italian" class="interlanguage-link-target"><span>Italiano</span></a></li><li class="interlanguage-link interwiki-he mw-list-item"><a href="https://he.wikipedia.org/wiki/%D7%A7%D7%A1%D7%99" title="קסי – Hebrew" lang="he" hreflang="he" data-title="קסי" data-language-autonym="עברית" data-language-local-name="Hebrew" class="interlanguage-link-target"><span>עברית</span></a></li><li class="interlanguage-link interwiki-ka mw-list-item"><a href="https://ka.wikipedia.org/wiki/%E1%83%A5%E1%83%A1%E1%83%98_(%E1%83%90%E1%83%A1%E1%83%9D)" title="ქსი (ასო) – Georgian" lang="ka" hreflang="ka" data-title="ქსი (ასო)" data-language-autonym="ქართული" data-language-local-name="Georgian" class="interlanguage-link-target"><span>ქართული</span></a></li><li class="interlanguage-link interwiki-sw mw-list-item"><a href="https://sw.wikipedia.org/wiki/Ksi" title="Ksi – Swahili" lang="sw" hreflang="sw" data-title="Ksi" data-language-autonym="Kiswahili" data-language-local-name="Swahili" class="interlanguage-link-target"><span>Kiswahili</span></a></li><li class="interlanguage-link interwiki-kv mw-list-item"><a href="https://kv.wikipedia.org/wiki/%D0%9A%D1%81%D0%B8" title="Кси – Komi" lang="kv" hreflang="kv" data-title="Кси" data-language-autonym="Коми" data-language-local-name="Komi" class="interlanguage-link-target"><span>Коми</span></a></li><li class="interlanguage-link interwiki-ht mw-list-item"><a href="https://ht.wikipedia.org/wiki/%CE%9E" title="Ξ – Haitian Creole" lang="ht" hreflang="ht" data-title="Ξ" data-language-autonym="Kreyòl ayisyen" data-language-local-name="Haitian Creole" class="interlanguage-link-target"><span>Kreyòl ayisyen</span></a></li><li class="interlanguage-link interwiki-ku mw-list-item"><a href="https://ku.wikipedia.org/wiki/Ks%C3%AE" title="Ksî – Kurdish" lang="ku" hreflang="ku" data-title="Ksî" data-language-autonym="Kurdî" data-language-local-name="Kurdish" class="interlanguage-link-target"><span>Kurdî</span></a></li><li class="interlanguage-link interwiki-la mw-list-item"><a href="https://la.wikipedia.org/wiki/Xi" title="Xi – Latin" lang="la" hreflang="la" data-title="Xi" data-language-autonym="Latina" data-language-local-name="Latin" class="interlanguage-link-target"><span>Latina</span></a></li><li class="interlanguage-link interwiki-lv mw-list-item"><a href="https://lv.wikipedia.org/wiki/Ks%C4%AB" title="Ksī – Latvian" lang="lv" hreflang="lv" data-title="Ksī" data-language-autonym="Latviešu" data-language-local-name="Latvian" class="interlanguage-link-target"><span>Latviešu</span></a></li><li class="interlanguage-link interwiki-lb mw-list-item"><a href="https://lb.wikipedia.org/wiki/Xi" title="Xi – Luxembourgish" lang="lb" hreflang="lb" data-title="Xi" data-language-autonym="Lëtzebuergesch" data-language-local-name="Luxembourgish" class="interlanguage-link-target"><span>Lëtzebuergesch</span></a></li><li class="interlanguage-link interwiki-lez mw-list-item"><a href="https://lez.wikipedia.org/wiki/%D0%9A%D1%81%D0%B8_(%D0%B3%D1%8C%D0%B0%D1%80%D1%84)" title="Кси (гьарф) – Lezghian" lang="lez" hreflang="lez" data-title="Кси (гьарф)" data-language-autonym="Лезги" data-language-local-name="Lezghian" class="interlanguage-link-target"><span>Лезги</span></a></li><li class="interlanguage-link interwiki-lt mw-list-item"><a href="https://lt.wikipedia.org/wiki/Ksi_(raid%C4%97)" title="Ksi (raidė) – Lithuanian" lang="lt" hreflang="lt" data-title="Ksi (raidė)" data-language-autonym="Lietuvių" data-language-local-name="Lithuanian" class="interlanguage-link-target"><span>Lietuvių</span></a></li><li class="interlanguage-link interwiki-hu mw-list-item"><a href="https://hu.wikipedia.org/wiki/Ksz%C3%AD" title="Kszí – Hungarian" lang="hu" hreflang="hu" data-title="Kszí" data-language-autonym="Magyar" data-language-local-name="Hungarian" class="interlanguage-link-target"><span>Magyar</span></a></li><li class="interlanguage-link interwiki-mr mw-list-item"><a href="https://mr.wikipedia.org/wiki/%E0%A4%9D%E0%A5%80_(%E0%A4%85%E0%A4%95%E0%A5%8D%E0%A4%B7%E0%A4%B0)" title="झी (अक्षर) – Marathi" lang="mr" hreflang="mr" data-title="झी (अक्षर)" data-language-autonym="मराठी" data-language-local-name="Marathi" class="interlanguage-link-target"><span>मराठी</span></a></li><li class="interlanguage-link interwiki-ms mw-list-item"><a href="https://ms.wikipedia.org/wiki/Xi" title="Xi – Malay" lang="ms" hreflang="ms" data-title="Xi" data-language-autonym="Bahasa Melayu" data-language-local-name="Malay" class="interlanguage-link-target"><span>Bahasa Melayu</span></a></li><li class="interlanguage-link interwiki-cdo mw-list-item"><a href="https://cdo.wikipedia.org/wiki/Xi_(c%C3%AA-m%C5%8D%CC%A4)" title="Xi (cê-mō̤) – Mindong" lang="cdo" hreflang="cdo" data-title="Xi (cê-mō̤)" data-language-autonym="閩東語 / Mìng-dĕ̤ng-ngṳ̄" data-language-local-name="Mindong" class="interlanguage-link-target"><span>閩東語 / Mìng-dĕ̤ng-ngṳ̄</span></a></li><li class="interlanguage-link interwiki-nah mw-list-item"><a href="https://nah.wikipedia.org/wiki/%CE%9E" title="Ξ – Nahuatl" lang="nah" hreflang="nah" data-title="Ξ" data-language-autonym="Nāhuatl" data-language-local-name="Nahuatl" class="interlanguage-link-target"><span>Nāhuatl</span></a></li><li class="interlanguage-link interwiki-nl mw-list-item"><a href="https://nl.wikipedia.org/wiki/Xi_(letter)" title="Xi (letter) – Dutch" lang="nl" hreflang="nl" data-title="Xi (letter)" data-language-autonym="Nederlands" data-language-local-name="Dutch" class="interlanguage-link-target"><span>Nederlands</span></a></li><li class="interlanguage-link interwiki-ja mw-list-item"><a href="https://ja.wikipedia.org/wiki/%CE%9E" title="Ξ – Japanese" lang="ja" hreflang="ja" data-title="Ξ" data-language-autonym="日本語" data-language-local-name="Japanese" class="interlanguage-link-target"><span>日本語</span></a></li><li class="interlanguage-link interwiki-no mw-list-item"><a href="https://no.wikipedia.org/wiki/Ksi" title="Ksi – Norwegian Bokmål" lang="nb" hreflang="nb" data-title="Ksi" data-language-autonym="Norsk bokmål" data-language-local-name="Norwegian Bokmål" class="interlanguage-link-target"><span>Norsk bokmål</span></a></li><li class="interlanguage-link interwiki-nn mw-list-item"><a href="https://nn.wikipedia.org/wiki/Ksi" title="Ksi – Norwegian Nynorsk" lang="nn" hreflang="nn" data-title="Ksi" data-language-autonym="Norsk nynorsk" data-language-local-name="Norwegian Nynorsk" class="interlanguage-link-target"><span>Norsk nynorsk</span></a></li><li class="interlanguage-link interwiki-oc mw-list-item"><a href="https://oc.wikipedia.org/wiki/Xi" title="Xi – Occitan" lang="oc" hreflang="oc" data-title="Xi" data-language-autonym="Occitan" data-language-local-name="Occitan" class="interlanguage-link-target"><span>Occitan</span></a></li><li class="interlanguage-link interwiki-pa mw-list-item"><a href="https://pa.wikipedia.org/wiki/%E0%A8%95%E0%A8%B8%E0%A9%80_(%E0%A8%85%E0%A9%B1%E0%A8%96%E0%A8%B0)" title="ਕਸੀ (ਅੱਖਰ) – Punjabi" lang="pa" hreflang="pa" data-title="ਕਸੀ (ਅੱਖਰ)" data-language-autonym="ਪੰਜਾਬੀ" data-language-local-name="Punjabi" class="interlanguage-link-target"><span>ਪੰਜਾਬੀ</span></a></li><li class="interlanguage-link interwiki-nds mw-list-item"><a href="https://nds.wikipedia.org/wiki/Xi" title="Xi – Low German" lang="nds" hreflang="nds" data-title="Xi" data-language-autonym="Plattdüütsch" data-language-local-name="Low German" class="interlanguage-link-target"><span>Plattdüütsch</span></a></li><li class="interlanguage-link interwiki-pl mw-list-item"><a href="https://pl.wikipedia.org/wiki/Ksi" title="Ksi – Polish" lang="pl" hreflang="pl" data-title="Ksi" data-language-autonym="Polski" data-language-local-name="Polish" class="interlanguage-link-target"><span>Polski</span></a></li><li class="interlanguage-link interwiki-pt mw-list-item"><a href="https://pt.wikipedia.org/wiki/%CE%9E" title="Ξ – Portuguese" lang="pt" hreflang="pt" data-title="Ξ" data-language-autonym="Português" data-language-local-name="Portuguese" class="interlanguage-link-target"><span>Português</span></a></li><li class="interlanguage-link interwiki-ro mw-list-item"><a href="https://ro.wikipedia.org/wiki/Csi_(liter%C4%83)" title="Csi (literă) – Romanian" lang="ro" hreflang="ro" data-title="Csi (literă)" data-language-autonym="Română" data-language-local-name="Romanian" class="interlanguage-link-target"><span>Română</span></a></li><li class="interlanguage-link interwiki-ru mw-list-item"><a href="https://ru.wikipedia.org/wiki/%D0%9A%D1%81%D0%B8_(%D0%B1%D1%83%D0%BA%D0%B2%D0%B0_%D0%B3%D1%80%D0%B5%D1%87%D0%B5%D1%81%D0%BA%D0%BE%D0%B3%D0%BE_%D0%B0%D0%BB%D1%84%D0%B0%D0%B2%D0%B8%D1%82%D0%B0)" title="Кси (буква греческого алфавита) – Russian" lang="ru" hreflang="ru" data-title="Кси (буква греческого алфавита)" data-language-autonym="Русский" data-language-local-name="Russian" class="interlanguage-link-target"><span>Русский</span></a></li><li class="interlanguage-link interwiki-simple mw-list-item"><a href="https://simple.wikipedia.org/wiki/Xi" title="Xi – Simple English" lang="en-simple" hreflang="en-simple" data-title="Xi" data-language-autonym="Simple English" data-language-local-name="Simple English" class="interlanguage-link-target"><span>Simple English</span></a></li><li class="interlanguage-link interwiki-sk mw-list-item"><a href="https://sk.wikipedia.org/wiki/Ks%C3%AD" title="Ksí – Slovak" lang="sk" hreflang="sk" data-title="Ksí" data-language-autonym="Slovenčina" data-language-local-name="Slovak" class="interlanguage-link-target"><span>Slovenčina</span></a></li><li class="interlanguage-link interwiki-sl mw-list-item"><a href="https://sl.wikipedia.org/wiki/Ksi" title="Ksi – Slovenian" lang="sl" hreflang="sl" data-title="Ksi" data-language-autonym="Slovenščina" data-language-local-name="Slovenian" class="interlanguage-link-target"><span>Slovenščina</span></a></li><li class="interlanguage-link interwiki-ckb mw-list-item"><a href="https://ckb.wikipedia.org/wiki/%DA%A9%D8%B3%DB%8C_(%D9%BE%DB%8C%D8%AA)" title="کسی (پیت) – Central Kurdish" lang="ckb" hreflang="ckb" data-title="کسی (پیت)" data-language-autonym="کوردی" data-language-local-name="Central Kurdish" class="interlanguage-link-target"><span>کوردی</span></a></li><li class="interlanguage-link interwiki-sr mw-list-item"><a href="https://sr.wikipedia.org/wiki/%D0%9A%D1%81%D0%B8_(%D1%81%D0%BB%D0%BE%D0%B2%D0%BE)" title="Кси (слово) – Serbian" lang="sr" hreflang="sr" data-title="Кси (слово)" data-language-autonym="Српски / srpski" data-language-local-name="Serbian" class="interlanguage-link-target"><span>Српски / srpski</span></a></li><li class="interlanguage-link interwiki-sh mw-list-item"><a href="https://sh.wikipedia.org/wiki/Ksi" title="Ksi – Serbo-Croatian" lang="sh" hreflang="sh" data-title="Ksi" data-language-autonym="Srpskohrvatski / српскохрватски" data-language-local-name="Serbo-Croatian" class="interlanguage-link-target"><span>Srpskohrvatski / српскохрватски</span></a></li><li class="interlanguage-link interwiki-fi mw-list-item"><a href="https://fi.wikipedia.org/wiki/Ksii" title="Ksii – Finnish" lang="fi" hreflang="fi" data-title="Ksii" data-language-autonym="Suomi" data-language-local-name="Finnish" class="interlanguage-link-target"><span>Suomi</span></a></li><li class="interlanguage-link interwiki-sv mw-list-item"><a href="https://sv.wikipedia.org/wiki/Xi_(bokstav)" title="Xi (bokstav) – Swedish" lang="sv" hreflang="sv" data-title="Xi (bokstav)" data-language-autonym="Svenska" data-language-local-name="Swedish" class="interlanguage-link-target"><span>Svenska</span></a></li><li class="interlanguage-link interwiki-th mw-list-item"><a href="https://th.wikipedia.org/wiki/%E0%B9%84%E0%B8%8B_(%E0%B8%AD%E0%B8%B1%E0%B8%81%E0%B8%A9%E0%B8%A3%E0%B8%81%E0%B8%A3%E0%B8%B5%E0%B8%81)" title="ไซ (อักษรกรีก) – Thai" lang="th" hreflang="th" data-title="ไซ (อักษรกรีก)" data-language-autonym="ไทย" data-language-local-name="Thai" class="interlanguage-link-target"><span>ไทย</span></a></li><li class="interlanguage-link interwiki-tr mw-list-item"><a href="https://tr.wikipedia.org/wiki/Ksi" title="Ksi – Turkish" lang="tr" hreflang="tr" data-title="Ksi" data-language-autonym="Türkçe" data-language-local-name="Turkish" class="interlanguage-link-target"><span>Türkçe</span></a></li><li class="interlanguage-link interwiki-uk mw-list-item"><a href="https://uk.wikipedia.org/wiki/%D0%9A%D1%81%D1%96_(%D0%BB%D1%96%D1%82%D0%B5%D1%80%D0%B0)" title="Ксі (літера) – Ukrainian" lang="uk" hreflang="uk" data-title="Ксі (літера)" data-language-autonym="Українська" data-language-local-name="Ukrainian" class="interlanguage-link-target"><span>Українська</span></a></li><li class="interlanguage-link interwiki-vep mw-list-item"><a href="https://vep.wikipedia.org/wiki/Ksi" title="Ksi – Veps" lang="vep" hreflang="vep" data-title="Ksi" data-language-autonym="Vepsän kel’" data-language-local-name="Veps" class="interlanguage-link-target"><span>Vepsän kel’</span></a></li><li class="interlanguage-link interwiki-vi mw-list-item"><a href="https://vi.wikipedia.org/wiki/Xi" title="Xi – Vietnamese" lang="vi" hreflang="vi" data-title="Xi" data-language-autonym="Tiếng Việt" data-language-local-name="Vietnamese" class="interlanguage-link-target"><span>Tiếng Việt</span></a></li><li class="interlanguage-link interwiki-war mw-list-item"><a href="https://war.wikipedia.org/wiki/Xi_(agi)" title="Xi (agi) – Waray" lang="war" hreflang="war" data-title="Xi (agi)" data-language-autonym="Winaray" data-language-local-name="Waray" class="interlanguage-link-target"><span>Winaray</span></a></li><li class="interlanguage-link interwiki-wuu mw-list-item"><a href="https://wuu.wikipedia.org/wiki/%CE%9E" title="Ξ – Wu" lang="wuu" hreflang="wuu" data-title="Ξ" data-language-autonym="吴语" data-language-local-name="Wu" class="interlanguage-link-target"><span>吴语</span></a></li><li class="interlanguage-link interwiki-zh-yue mw-list-item"><a href="https://zh-yue.wikipedia.org/wiki/%CE%9E" title="Ξ – Cantonese" lang="yue" hreflang="yue" data-title="Ξ" data-language-autonym="粵語" data-language-local-name="Cantonese" class="interlanguage-link-target"><span>粵語</span></a></li><li class="interlanguage-link interwiki-diq mw-list-item"><a href="https://diq.wikipedia.org/wiki/%CE%9E" title="Ξ – Zazaki" lang="diq" hreflang="diq" data-title="Ξ" data-language-autonym="Zazaki" data-language-local-name="Zazaki" class="interlanguage-link-target"><span>Zazaki</span></a></li><li class="interlanguage-link interwiki-zh mw-list-item"><a href="https://zh.wikipedia.org/wiki/%CE%9E" title="Ξ – Chinese" lang="zh" hreflang="zh" data-title="Ξ" data-language-autonym="中文" data-language-local-name="Chinese" class="interlanguage-link-target"><span>中文</span></a></li><li class="interlanguage-link interwiki-kge mw-list-item"><a href="https://kge.wikipedia.org/wiki/%CE%9E_(Xi)" title="Ξ (Xi) – Komering" lang="kge" hreflang="kge" data-title="Ξ (Xi)" data-language-autonym="Kumoring" data-language-local-name="Komering" class="interlanguage-link-target"><span>Kumoring</span></a></li> </ul> <div class="after-portlet after-portlet-lang"><span class="wb-langlinks-edit wb-langlinks-link"><a href="https://www.wikidata.org/wiki/Special:EntityPage/Q14406#sitelinks-wikipedia" title="Edit interlanguage links" class="wbc-editpage">Edit links</a></span></div> </div> </div> </div> </header> <div class="vector-page-toolbar"> <div class="vector-page-toolbar-container"> <div id="left-navigation"> <nav aria-label="Namespaces"> <div id="p-associated-pages" class="vector-menu vector-menu-tabs mw-portlet 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Unsourced material may be challenged and removed.<br /><small><span class="plainlinks"><i>Find sources:</i> <a rel="nofollow" class="external text" href="https://www.google.com/search?as_eq=wikipedia&q=%22Xi%22+letter">"Xi" letter</a> – <a rel="nofollow" class="external text" href="https://www.google.com/search?tbm=nws&q=%22Xi%22+letter+-wikipedia&tbs=ar:1">news</a> <b>·</b> <a rel="nofollow" class="external text" href="https://www.google.com/search?&q=%22Xi%22+letter&tbs=bkt:s&tbm=bks">newspapers</a> <b>·</b> <a rel="nofollow" class="external text" href="https://www.google.com/search?tbs=bks:1&q=%22Xi%22+letter+-wikipedia">books</a> <b>·</b> <a rel="nofollow" class="external text" href="https://scholar.google.com/scholar?q=%22Xi%22+letter">scholar</a> <b>·</b> <a rel="nofollow" class="external text" href="https://www.jstor.org/action/doBasicSearch?Query=%22Xi%22+letter&acc=on&wc=on">JSTOR</a></span></small></span> <span class="date-container"><i>(<span class="date">June 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href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><table class="sidebar nomobile nowraplinks greek-alphabet-sidebar" style="width:20em"><tbody><tr><td class="sidebar-top-image"><span class="skin-invert" typeof="mw:File"><a href="/wiki/File:Xi_uc_lc.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/c/cd/Xi_uc_lc.svg/100px-Xi_uc_lc.svg.png" decoding="async" width="100" height="67" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/c/cd/Xi_uc_lc.svg/150px-Xi_uc_lc.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/c/cd/Xi_uc_lc.svg/200px-Xi_uc_lc.svg.png 2x" data-file-width="3000" data-file-height="2000" /></a></span></td></tr><tr><th class="sidebar-title"><a href="/wiki/Greek_alphabet" title="Greek alphabet">Greek alphabet</a></th></tr><tr><td class="sidebar-content hlist"> <table style="width:100%;border-collapse:collapse;border-spacing:0px 0px;border:none;margin-left:0.7em;text-align:left;"><tbody><tr style="vertical-align:top"><td> Αα</td><td style="padding-right:1.0em;"> <a href="/wiki/Alpha" title="Alpha">Alpha</a></td><td> Νν</td><td style="padding-right:0.6em;"> <a href="/wiki/Nu_(letter)" title="Nu (letter)">Nu</a></td></tr><tr style="vertical-align:top"><td> Ββ</td><td style="padding-right:1.0em;"> <a href="/wiki/Beta" title="Beta">Beta</a></td><td> Ξξ</td><td style="padding-right:0.6em;"> <a class="mw-selflink selflink">Xi</a></td></tr><tr style="vertical-align:top"><td> Γγ</td><td style="padding-right:1.0em;"> <a href="/wiki/Gamma" title="Gamma">Gamma</a></td><td> Οο</td><td style="padding-right:0.6em;"> <a href="/wiki/Omicron" title="Omicron">Omicron</a></td></tr><tr style="vertical-align:top"><td> Δδ</td><td style="padding-right:1.0em;"> <a href="/wiki/Delta_(letter)" title="Delta (letter)">Delta</a></td><td> Ππ</td><td style="padding-right:0.6em;"> <a href="/wiki/Pi_(letter)" title="Pi (letter)">Pi</a></td></tr><tr style="vertical-align:top"><td> Εε</td><td style="padding-right:1.0em;"> <a href="/wiki/Epsilon" title="Epsilon">Epsilon</a></td><td> Ρρ</td><td style="padding-right:0.6em;"> <a href="/wiki/Rho" title="Rho">Rho</a></td></tr><tr style="vertical-align:top"><td> Ζζ</td><td style="padding-right:1.0em;"> <a href="/wiki/Zeta" title="Zeta">Zeta</a></td><td> Σσς</td><td style="padding-right:0.6em;"> <a href="/wiki/Sigma" title="Sigma">Sigma</a></td></tr><tr style="vertical-align:top"><td> Ηη</td><td style="padding-right:1.0em;"> <a href="/wiki/Eta" title="Eta">Eta</a></td><td> Ττ</td><td style="padding-right:0.6em;"> <a href="/wiki/Tau" title="Tau">Tau</a></td></tr><tr style="vertical-align:top"><td> Θθ</td><td style="padding-right:1.0em;"> <a href="/wiki/Theta" title="Theta">Theta</a></td><td> Υυ</td><td style="padding-right:0.6em;"> <a href="/wiki/Upsilon" title="Upsilon">Upsilon</a></td></tr><tr style="vertical-align:top"><td> Ιι</td><td style="padding-right:1.0em;"> <a href="/wiki/Iota" title="Iota">Iota</a></td><td> Φφ</td><td style="padding-right:0.6em;"> <a href="/wiki/Phi" title="Phi">Phi</a></td></tr><tr style="vertical-align:top"><td> Κκ</td><td style="padding-right:1.0em;"> <a href="/wiki/Kappa" title="Kappa">Kappa</a></td><td> Χχ</td><td style="padding-right:0.6em;"> <a href="/wiki/Chi_(letter)" title="Chi (letter)">Chi</a></td></tr><tr style="vertical-align:top"><td> Λλ</td><td style="padding-right:1.0em;"> <a href="/wiki/Lambda" title="Lambda">Lambda</a></td><td> Ψψ</td><td style="padding-right:0.6em;"> <a href="/wiki/Psi_(Greek)" title="Psi (Greek)">Psi</a></td></tr><tr style="vertical-align:top"><td> Μμ</td><td style="padding-right:1.0em;"> <a href="/wiki/Mu_(letter)" title="Mu (letter)">Mu</a></td><td> Ωω</td><td style="padding-right:0.6em;"> <a href="/wiki/Omega" title="Omega">Omega</a></td></tr></tbody></table></td> </tr><tr><th class="sidebar-heading"> <a href="/wiki/History_of_the_Greek_alphabet" title="History of the Greek alphabet">History</a></th></tr><tr><td class="sidebar-content hlist"> <div style="display:inline-block; padding:0.2em 0.4em; line-height:1.2em; line-height:1.1em;padding-bottom:0.45em;"> <a href="/wiki/Archaic_Greek_alphabets" title="Archaic Greek alphabets"><b>Archaic local variants</b></a></div> <table style="width:100%;border-collapse:collapse;border-spacing:0px 0px;border:none;margin-left:0.7em;text-align:left;"><tbody><tr style="vertical-align:top"><td> Ϝ</td><td style="padding-right:1.0em;"> <a href="/wiki/Digamma" title="Digamma">Digamma</a></td><td> Ͱ</td><td style="padding-right:0.6em;"> <a href="/wiki/Heta" title="Heta">Heta</a></td></tr><tr style="vertical-align:top"><td> Ϻ</td><td style="padding-right:1.0em;"> <a href="/wiki/San_(letter)" title="San (letter)">San</a></td><td> Ϙ</td><td style="padding-right:0.6em;"> <a href="/wiki/Koppa_(letter)" title="Koppa (letter)">Koppa</a></td></tr><tr style="vertical-align:top"><td> Ͷ</td><td style="padding-right:1.0em;"> <div class="hlist inline"><ul><li><a href="/wiki/Tsan" class="mw-redirect" title="Tsan">Tsan</a></li><li><a href="/wiki/Digamma#Pamphylian_digamma" title="Digamma">Digamma</a></li></ul></div></td><td> Ͳ</td><td style="padding-right:0.6em;"> <a href="/wiki/Sampi" title="Sampi">Sampi</a></td></tr></tbody></table></td> </tr><tr><th class="sidebar-heading"> Diacritics and other symbols</th></tr><tr><td class="sidebar-content hlist"> <div style="display:inline-block; padding:0.2em 0.4em; line-height:1.2em; padding-top:0.3em;line-height:1.1em;padding-bottom:0;"><a href="/wiki/Greek_diacritics" title="Greek diacritics">Diacritics</a></div> <div class="hlist"><ul><li><a href="/wiki/Acute_accent" title="Acute accent">ά</a></li><li><a href="/wiki/Grave_accent" title="Grave accent">ὰ</a></li><li><a href="/wiki/Circumflex" title="Circumflex">ᾶ</a></li><li><a href="/wiki/Smooth_breathing" title="Smooth breathing">ἀ</a></li><li><a href="/wiki/Rough_breathing" title="Rough breathing">ἁ</a></li><li><a href="/wiki/Macron_(diacritic)" title="Macron (diacritic)">ᾱ</a></li><li><a href="/wiki/Breve" title="Breve">ᾰ</a></li><li><a href="/wiki/Diaeresis_(diacritic)" title="Diaeresis (diacritic)">ϊ</a></li><li><a href="/wiki/Iota_subscript" title="Iota subscript">ᾳ</a></li><li><a href="/wiki/Caron" title="Caron">σ̌</a></li></ul></div> <div style="display:inline-block; padding:0.2em 0.4em; line-height:1.2em; padding-top:0.3em;line-height:1.1em;padding-bottom:0;"><a href="/wiki/Greek_ligatures" title="Greek ligatures">Ligatures</a></div> <div class="hlist"><ul><li style="font-size:110%;"><a href="/wiki/Kai_(conjunction)" title="Kai (conjunction)">ϗ</a></li><li style="font-size:110%;"><a href="/wiki/Stigma_(ligature)" title="Stigma (ligature)">ϛ</a></li></ul></div> <div style="display:inline-block; padding:0.2em 0.4em; line-height:1.2em; padding-top:0.3em;line-height:1.1em;padding-bottom:0;"> <a href="/wiki/Greek_numerals" title="Greek numerals">Numerals</a> (<a href="/wiki/Attic_numerals" title="Attic numerals">Attic</a>)</div> <div class="hlist"><ul><li style="font-size:110%;"><a href="/wiki/Digamma" title="Digamma">ϛ <span style="font-size:85%;">(6)</span></a></li><li style="font-size:110%;"><a href="/wiki/Koppa_(letter)" title="Koppa (letter)">ϟ <span style="font-size:85%;">(90)</span></a></li><li style="font-size:110%;"><a href="/wiki/Sampi" title="Sampi">ϡ <span style="font-size:85%;">(900)</span></a></li></ul></div></td> </tr><tr><th class="sidebar-heading"> Related topics</th></tr><tr><td class="sidebar-content hlist"> <ul><li><a href="/wiki/Greek_letters_used_in_mathematics,_science,_and_engineering" title="Greek letters used in mathematics, science, and engineering">Use as scientific symbols</a></li> <li><a href="/wiki/Greek_orthography" title="Greek orthography">Orthography</a></li> <li><a href="/wiki/Romanization_of_Greek" title="Romanization of Greek">Romanization</a></li> <li><a href="/wiki/Cyrillization_of_Greek" title="Cyrillization of Greek">Cyrillization</a></li></ul></td> </tr><tr><td class="sidebar-below plainlist"> <div class="hlist"> <ul><li><span class="noviewer" typeof="mw:File"><span title="Category"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/9/96/Symbol_category_class.svg/16px-Symbol_category_class.svg.png" decoding="async" width="16" height="16" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/9/96/Symbol_category_class.svg/23px-Symbol_category_class.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/9/96/Symbol_category_class.svg/31px-Symbol_category_class.svg.png 2x" data-file-width="180" data-file-height="185" /></span></span> <a href="/wiki/Category:Greek_letters" title="Category:Greek letters">Category</a></li></ul> </div></td></tr><tr><td class="sidebar-navbar"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><style data-mw-deduplicate="TemplateStyles:r1239400231">.mw-parser-output .navbar{display:inline;font-size:88%;font-weight:normal}.mw-parser-output .navbar-collapse{float:left;text-align:left}.mw-parser-output .navbar-boxtext{word-spacing:0}.mw-parser-output .navbar ul{display:inline-block;white-space:nowrap;line-height:inherit}.mw-parser-output .navbar-brackets::before{margin-right:-0.125em;content:"[ "}.mw-parser-output .navbar-brackets::after{margin-left:-0.125em;content:" ]"}.mw-parser-output .navbar li{word-spacing:-0.125em}.mw-parser-output .navbar a>span,.mw-parser-output .navbar a>abbr{text-decoration:inherit}.mw-parser-output .navbar-mini abbr{font-variant:small-caps;border-bottom:none;text-decoration:none;cursor:inherit}.mw-parser-output .navbar-ct-full{font-size:114%;margin:0 7em}.mw-parser-output .navbar-ct-mini{font-size:114%;margin:0 4em}html.skin-theme-clientpref-night .mw-parser-output .navbar li a abbr{color:var(--color-base)!important}@media(prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .navbar li a abbr{color:var(--color-base)!important}}@media print{.mw-parser-output .navbar{display:none!important}}</style><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Greek_alphabet_sidebar" title="Template:Greek alphabet sidebar"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Greek_alphabet_sidebar" title="Template talk:Greek alphabet sidebar"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Greek_alphabet_sidebar" title="Special:EditPage/Template:Greek alphabet sidebar"><abbr title="Edit this template">e</abbr></a></li></ul></div></td></tr></tbody></table> <p><b>Xi</b> (<span class="rt-commentedText nowrap"><span class="IPA nopopups noexcerpt" lang="en-fonipa"><a href="/wiki/Help:IPA/English" title="Help:IPA/English">/<span style="border-bottom:1px dotted"><span title="'z' in 'zoom'">z</span><span title="/aɪ/: 'i' in 'tide'">aɪ</span></span>/</a></span></span> <a href="/wiki/Help:Pronunciation_respelling_key" title="Help:Pronunciation respelling key"><i title="English pronunciation respelling"><span style="font-size:90%">ZY</span></i></a> or <span class="rt-commentedText nowrap"><span class="IPA nopopups noexcerpt" lang="en-fonipa"><a href="/wiki/Help:IPA/English" title="Help:IPA/English">/(<span style="border-bottom:1px dotted"><span title="'k' in 'kind'">k</span></span>)<span style="border-bottom:1px dotted"><span title="'s' in 'sigh'">s</span><span title="/aɪ/: 'i' in 'tide'">aɪ</span></span>/</a></span></span> <a href="/wiki/Help:Pronunciation_respelling_key" title="Help:Pronunciation respelling key"><i title="English pronunciation respelling"><span style="font-size:90%">(K)SY</span></i></a>;<sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> uppercase <b>Ξ</b>, lowercase <b>ξ</b>; <a href="/wiki/Greek_language" title="Greek language">Greek</a>: <span lang="el">ξι</span>) is the fourteenth letter of the <a href="/wiki/Greek_alphabet" title="Greek alphabet">Greek alphabet</a>, representing the voiceless <a href="/wiki/Consonant_cluster" title="Consonant cluster">consonant cluster</a> <span class="IPA nowrap" lang="el-Latn-fonipa"><a href="/wiki/Help:IPA/Greek" title="Help:IPA/Greek">[ks]</a></span>. Its name is pronounced <span class="IPA nowrap" lang="el-Latn-fonipa"><a href="/wiki/Help:IPA/Greek" title="Help:IPA/Greek">[ksi]</a></span> in <a href="/wiki/Modern_Greek" title="Modern Greek">Modern Greek</a>. In the system of <a href="/wiki/Greek_numerals" title="Greek numerals">Greek numerals</a>, it has a value of 60. Xi was derived from the <a href="/wiki/Phoenician_alphabet" title="Phoenician alphabet">Phoenician letter</a> <a href="/wiki/Samekh" title="Samekh">samekh</a> <span typeof="mw:File"><a href="/wiki/File:Phoenician_samekh.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/8/8f/Phoenician_samekh.svg/20px-Phoenician_samekh.svg.png" decoding="async" width="20" height="20" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/8/8f/Phoenician_samekh.svg/30px-Phoenician_samekh.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/8/8f/Phoenician_samekh.svg/40px-Phoenician_samekh.svg.png 2x" data-file-width="85" data-file-height="85" /></a></span>. </p><p>Xi is distinct from the letter <a href="/wiki/Chi_(letter)" title="Chi (letter)">chi</a>, which gave its form to the Latin letter <a href="/wiki/X" title="X">X</a>. </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="Greek">Greek</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Xi_(letter)&action=edit&section=1" title="Edit section: Greek"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size mw-halign-left" typeof="mw:File/Thumb"><a href="/wiki/File:Xi_alternate.png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/1/1e/Xi_alternate.png" decoding="async" width="45" height="54" class="mw-file-element" data-file-width="45" data-file-height="54" /></a><figcaption>A joined variant of Ξ (<i>New Athena Unicode</i> font)</figcaption></figure> <p>Both in classical <a href="/wiki/Ancient_Greek" title="Ancient Greek">Ancient Greek</a> and in <a href="/wiki/Modern_Greek" title="Modern Greek">Modern Greek</a>, the letter Ξ represents the consonant cluster /ks/. In some <a href="/wiki/Archaic_Greek_alphabets" title="Archaic Greek alphabets">archaic local variants</a> of the Greek alphabet, this letter was missing. Instead, especially in the dialects of most of the Greek mainland and <a href="/wiki/Euboea" title="Euboea">Euboea</a>, the cluster /ks/ was represented by Χ (which in classical Greek is <a href="/wiki/Chi_(letter)" title="Chi (letter)">chi</a>, used for <span class="IPA nowrap" lang="und-Latn-fonipa" title="Representation in the International Phonetic Alphabet (IPA)">/kʰ/</span>). </p><p>Because this variant of the Greek alphabet was used in <a href="/wiki/Magna_Graecia" title="Magna Graecia">Magna Graecia</a> (the Greek colonies in <a href="/wiki/Sicily" title="Sicily">Sicily</a> and the southern part of the <a href="/wiki/Italian_peninsula" title="Italian peninsula">Italian peninsula</a>), the <a href="/wiki/Latin_alphabet" title="Latin alphabet">Latin alphabet</a> borrowed Χ rather than Ξ as the Latin letter that represented the /ks/ cluster that was also present in Latin. </p> <div class="mw-heading mw-heading2"><h2 id="Cyrillic">Cyrillic</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Xi_(letter)&action=edit&section=2" title="Edit section: Cyrillic"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The Xi was adopted into the <a href="/wiki/Early_Cyrillic_alphabet" title="Early Cyrillic alphabet">early Cyrillic alphabet</a>, as the letter <a href="/wiki/Ksi_(Cyrillic_letter)" class="mw-redirect" title="Ksi (Cyrillic letter)">ksi</a> (Ѯ, ѯ). </p> <div class="mw-heading mw-heading2"><h2 id="Mathematics_and_science">Mathematics and science</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Xi_(letter)&action=edit&section=3" title="Edit section: Mathematics and science"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <div class="mw-heading mw-heading3"><h3 id="Uppercase">Uppercase</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Xi_(letter)&action=edit&section=4" title="Edit section: Uppercase"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The uppercase letter Ξ is used as a symbol in various contexts. </p> <div class="mw-heading mw-heading4"><h4 id="Pure_mathematics">Pure mathematics</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Xi_(letter)&action=edit&section=5" title="Edit section: Pure mathematics"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/Harish-Chandra%27s_%CE%9E_function" title="Harish-Chandra's Ξ function">Harish-Chandra's Ξ function</a> in <a href="/wiki/Harmonic_analysis" title="Harmonic analysis">harmonic analysis</a> and <a href="/wiki/Representation_theory" title="Representation theory">representation theory</a></li> <li>The <a href="/wiki/Riemann_Xi_function" class="mw-redirect" title="Riemann Xi function">Riemann Xi function</a> in <a href="/wiki/Analytic_number_theory" title="Analytic number theory">analytic number theory</a> and <a href="/wiki/Complex_analysis" title="Complex analysis">complex analysis</a></li></ul> <div class="mw-heading mw-heading4"><h4 id="Physics">Physics</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Xi_(letter)&action=edit&section=6" title="Edit section: Physics"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li>The "<a href="/wiki/Xi_baryon" title="Xi baryon">cascade particles</a>" in particle physics</li> <li>The <a href="/wiki/Partition_function_(statistical_mechanics)" title="Partition function (statistical mechanics)">partition function</a> under the <a href="/wiki/Grand_canonical_ensemble" title="Grand canonical ensemble">grand canonical ensemble</a> in statistical mechanics</li></ul> <div class="mw-heading mw-heading4"><h4 id="Other_uses">Other uses</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Xi_(letter)&action=edit&section=7" title="Edit section: Other uses"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li>Indicating "no change of state" in <a href="/wiki/Z_notation" title="Z notation">Z notation</a> in <a href="/wiki/Computing" title="Computing">computing</a></li> <li>Used as the <a href="/wiki/Latin" title="Latin">Latin</a> letter <a href="/wiki/E" title="E">E</a> in some logos.</li> <li>Monetary units of the <a href="/wiki/Cryptocurrency" title="Cryptocurrency">cryptocurrencies</a> <a href="/wiki/Ethereum#Ether" title="Ethereum">Ether</a> (and less commonly <a href="/wiki/Ethereum_Classic" title="Ethereum Classic">ETC</a>), equal to 10<sup>18</sup> Wei</li></ul> <div class="mw-heading mw-heading3"><h3 id="Lowercase">Lowercase</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Xi_(letter)&action=edit&section=8" title="Edit section: Lowercase"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The lowercase letter ξ is used as a symbol for: </p> <div class="mw-heading mw-heading4"><h4 id="Pure_mathematics_2">Pure mathematics</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Xi_(letter)&action=edit&section=9" title="Edit section: Pure mathematics"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/Random_variable" title="Random variable">Random variables</a></li> <li>A parameter in a <a href="/wiki/Generalized_Pareto_distribution" title="Generalized Pareto distribution">generalized Pareto distribution</a></li> <li>The symmetric function equation of the <a href="/wiki/Riemann_zeta_function" title="Riemann zeta function">Riemann zeta function</a> in mathematics, also known as the <a href="/wiki/Riemann_Xi_function" class="mw-redirect" title="Riemann Xi function">Riemann Xi function</a></li> <li>A <a href="/wiki/Universal_set" title="Universal set">universal set</a> in <a href="/wiki/Set_theory" title="Set theory">set theory</a></li> <li>A number used in the remainder term of <a href="/wiki/Taylor%27s_theorem" title="Taylor's theorem">Taylor's theorem</a> that falls between the limits <i>a</i> and <i>b</i></li> <li>A number used in error approximations for formulas that are applications of Taylor's theorem, such as <a href="/wiki/Newton%E2%80%93Cotes_formulas" title="Newton–Cotes formulas">Newton–Cotes formulas</a></li></ul> <div class="mw-heading mw-heading4"><h4 id="Physics_and_astronomy">Physics and astronomy</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Xi_(letter)&action=edit&section=10" title="Edit section: Physics and astronomy"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li>In fluid dynamics, the <a href="/wiki/Iribarren_parameter" class="mw-redirect" title="Iribarren parameter">Iribarren parameter</a>.</li> <li>The <a href="/wiki/Initial_mass_function" title="Initial mass function">initial mass function</a> in <a href="/wiki/Astronomy" title="Astronomy">astronomy</a>.</li> <li>The <a href="/wiki/Correlation_function_(astronomy)" title="Correlation function (astronomy)">correlation function</a> in <a href="/wiki/Astronomy" title="Astronomy">astronomy</a>.</li> <li><a href="/wiki/Spatial_frequency" title="Spatial frequency">Spatial frequency</a>;<sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> also sometimes temporal <a href="/wiki/Frequency" title="Frequency">frequency</a>.</li> <li>A small displacement in MHD <a href="/wiki/Plasma_stability" title="Plasma stability">plasma stability</a> theory</li> <li>The x-coordinate of computational space as used in <a href="/wiki/Computational_fluid_dynamics" title="Computational fluid dynamics">computational fluid dynamics</a></li> <li><a href="/wiki/Electric_potential_energy" title="Electric potential energy">Potential difference</a> in physics (in volts)</li> <li>The radial integral in the spin-orbit matrix operator in <a href="/wiki/Atomic_physics" title="Atomic physics">atomic physics</a>.</li> <li>The <a href="/wiki/Killing_vector_field" title="Killing vector field">Killing vector</a> in general relativity.</li> <li>Average logarithmic energy decrement per collision (neutron calculations in nuclear physics)</li> <li><a href="/w/index.php?title=Pippard%27s_cohesion_length&action=edit&redlink=1" class="new" title="Pippard's cohesion length (page does not exist)">Pippard's cohesion length</a> in <a href="/wiki/Superconductors" class="mw-redirect" title="Superconductors">superconductors</a></li> <li>The diameter of a crystal nucleus in <a href="/wiki/Nucleation" title="Nucleation">nucleation</a> theory</li> <li><a href="/wiki/Microturbulence" title="Microturbulence">Microturbulence</a> velocity in a stellar atmosphere</li> <li>The dimensionless longitudinal momentum loss of a beam particle after a two-body interaction in accelerator physics.</li> <li>Dimensionless distance variable used in the <a href="/wiki/Lane%E2%80%93Emden_equation" title="Lane–Emden equation">Lane–Emden equation</a></li></ul> <div class="mw-heading mw-heading4"><h4 id="Other_uses_2">Other uses</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Xi_(letter)&action=edit&section=11" title="Edit section: Other uses"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li>Propositional variables in some philosophical works, first found in Wittgenstein's <a href="/wiki/Tractatus_Logico-Philosophicus" title="Tractatus Logico-Philosophicus">Tractatus</a></li> <li><a href="/wiki/Extent_of_reaction" title="Extent of reaction">Extent of reaction</a>, a concept in <a href="/wiki/Physical_chemistry" title="Physical chemistry">physical chemistry</a><sup id="cite_ref-4" class="reference"><a href="#cite_note-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> used often in <a href="/wiki/Chemical_engineering" title="Chemical engineering">chemical engineering</a> kinetics and <a href="/wiki/Thermochemistry" title="Thermochemistry">thermochemistry</a></li> <li>Unknown <a href="/wiki/Stereochemistry" title="Stereochemistry">stereochemistry</a> or <a href="/wiki/Stereocentre" class="mw-redirect" title="Stereocentre">stereocentre</a> configuration in a planar <a href="/wiki/Ring_(chemistry)" title="Ring (chemistry)">ring system</a> in <a href="/wiki/Organic_chemistry" title="Organic chemistry">organic chemistry</a>,<sup id="cite_ref-BuckinghamCooper2015_5-0" class="reference"><a href="#cite_note-BuckinghamCooper2015-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> as well as uppercase Xi for unknown <i>R</i>/<i>S</i>/<i>E</i>/<i>Z</i> configuration in general<sup id="cite_ref-6" class="reference"><a href="#cite_note-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup></li> <li>One of the two different polypeptide chains of the human embryonic <a href="/wiki/Hemoglobin" title="Hemoglobin">hemoglobin</a> types Hb-Portland (ξ<sub>2</sub>γ<sub>2</sub>) and Hb-Gower I (ξ<sub>2</sub>ε<sub>2</sub>)</li> <li>A parameter denoted as <a href="/w/index.php?title=Warped_time&action=edit&redlink=1" class="new" title="Warped time (page does not exist)">warped time</a> used to derive the equations for homogeneous <a href="/wiki/Azeotropic_distillation" title="Azeotropic distillation">azeotropic distillation</a></li> <li>State Price Density in <a href="/wiki/Mathematical_finance" title="Mathematical finance">mathematical finance</a></li> <li>The information vector in the <a href="/wiki/Information_Filter" class="mw-redirect" title="Information Filter">Information Filter</a>, <a href="/wiki/GraphSLAM" class="mw-redirect" title="GraphSLAM">GraphSLAM</a>, and a number of other algorithms used for <a href="/wiki/Robot_localization" class="mw-redirect" title="Robot localization">robot localization</a> and <a href="/wiki/Robotic_mapping" title="Robotic mapping">robotic mapping</a>.</li> <li>Used in <a href="/wiki/Support-vector_machine" class="mw-redirect" title="Support-vector machine">Support Vector machines</a> in cases where the data is not <a href="/wiki/Linear_separability" title="Linear separability">linearly separable</a>.</li> <li>Used in <a href="/wiki/Microelectronics" title="Microelectronics">Microelectronics</a> to represent the distance from a <a href="/wiki/P-n_junction" class="mw-redirect" title="P-n junction">p-n junction</a> to a point in the <a href="/wiki/Depletion_region" title="Depletion region">depletion region</a> where the <a href="/wiki/Electric_field" title="Electric field">electric field</a> is strongest.</li></ul> <div class="mw-heading mw-heading2"><h2 id="Other_uses_3">Other uses</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Xi_(letter)&action=edit&section=12" title="Edit section: Other uses"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Net_Servi%C3%A7os_de_Comunica%C3%A7%C3%A3o.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/c/c9/Net_Servi%C3%A7os_de_Comunica%C3%A7%C3%A3o.svg/220px-Net_Servi%C3%A7os_de_Comunica%C3%A7%C3%A3o.svg.png" decoding="async" width="220" height="81" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/c/c9/Net_Servi%C3%A7os_de_Comunica%C3%A7%C3%A3o.svg/330px-Net_Servi%C3%A7os_de_Comunica%C3%A7%C3%A3o.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/c/c9/Net_Servi%C3%A7os_de_Comunica%C3%A7%C3%A3o.svg/440px-Net_Servi%C3%A7os_de_Comunica%C3%A7%C3%A3o.svg.png 2x" data-file-width="564" data-file-height="208" /></a><figcaption>Ξ for E in a commercial logo</figcaption></figure> <ul><li><i><span class="noviewer" typeof="mw:File"><a href="/wiki/File:Commons-logo.svg" class="mw-file-description"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/12px-Commons-logo.svg.png" decoding="async" width="12" height="16" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/18px-Commons-logo.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/24px-Commons-logo.svg.png 2x" data-file-width="1024" data-file-height="1376" /></a></span> Media related to <a href="https://commons.wikimedia.org/wiki/Category:Xi_(letter)" class="extiw" title="commons:Category:Xi (letter)">Xi (letter)</a> at Wikimedia Commons</i></li></ul> <p>Uppercase Ξ is used as an 'E' to stylise company names/logos like <a href="/wiki/Razer_Inc" class="mw-redirect" title="Razer Inc">Razer</a> (styled as <b>RΛZΞR</b>), <a href="/wiki/Tesla,_Inc." title="Tesla, Inc.">Tesla</a> (styled as <b>TΞSLA</b>), the presidential campaigns of <a href="/wiki/Joe_Biden_2020_presidential_campaign" title="Joe Biden 2020 presidential campaign">Joe Biden</a> (styled as <b>BIDΞN</b>), musician <a href="/wiki/Banners_(musician)" title="Banners (musician)">Banners</a> (styled as <b>BANNΞRS</b>), and in South Korean boy group <a href="/wiki/ZE:A" title="ZE:A">ZE:A</a>'s newest logo (styled as "ZΞA") (Compare: <a href="/wiki/Heavy_Metal_umlaut" class="mw-redirect" title="Heavy Metal umlaut">Heavy Metal umlaut</a>; <a href="/wiki/Faux_Cyrillic" title="Faux Cyrillic">Faux Cyrillic</a>) </p> <div class="mw-heading mw-heading2"><h2 id="Unicode">Unicode</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Xi_(letter)&action=edit&section=13" title="Edit section: Unicode"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Unicode Code Charts: <a rel="nofollow" class="external text" href="https://www.unicode.org/charts/PDF/U0370.pdf">Greek and Coptic (Range: 0370-03FF)</a> </p> <ul><li><span class="nowrap"><style data-mw-deduplicate="TemplateStyles:r886049734">.mw-parser-output .monospaced{font-family:monospace,monospace}</style><span class="monospaced">U+039E</span> </span><span style="font-size:125%;line-height:1em">Ξ</span> <span style="font-variant: small-caps; text-transform: lowercase;">GREEK CAPITAL LETTER XI</span> (<link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734"><span class="monospaced">&Xi;</span>) (<code class="mw-highlight mw-highlight-lang-text mw-content-ltr" style="" dir="ltr">\Xi</code> in TeX)</li> <li><span class="nowrap"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734"><span class="monospaced">U+03BE</span> </span><span style="font-size:125%;line-height:1em">ξ</span> <span style="font-variant: small-caps; text-transform: lowercase;">GREEK SMALL LETTER XI</span> (<link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734"><span class="monospaced">&xi;</span>) (<code class="mw-highlight mw-highlight-lang-text mw-content-ltr" style="" dir="ltr">\xi</code> in TeX)</li> <li><span class="nowrap"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734"><span class="monospaced">U+2C9C</span> </span><span style="font-size:125%;line-height:1em">Ⲝ</span> <span style="font-variant: small-caps; text-transform: lowercase;">COPTIC CAPITAL LETTER KSI</span></li> <li><span class="nowrap"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734"><span class="monospaced">U+2C9D</span> </span><span style="font-size:125%;line-height:1em">ⲝ</span> <span style="font-variant: small-caps; text-transform: lowercase;">COPTIC SMALL LETTER KSI</span></li></ul> <p>The following 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: </p> <ul><li><span class="nowrap"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734"><span class="monospaced">U+1D6B5</span> </span><span style="font-size:125%;line-height:1em">𝚵</span> <span style="font-variant: small-caps; text-transform: lowercase;">MATHEMATICAL BOLD CAPITAL XI</span></li> <li><span class="nowrap"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734"><span class="monospaced">U+1D6CF</span> </span><span style="font-size:125%;line-height:1em">𝛏</span> <span style="font-variant: small-caps; text-transform: lowercase;">MATHEMATICAL BOLD SMALL XI</span></li> <li><span class="nowrap"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734"><span class="monospaced">U+1D6EF</span> </span><span style="font-size:125%;line-height:1em">𝛯</span> <span style="font-variant: small-caps; text-transform: lowercase;">MATHEMATICAL ITALIC CAPITAL XI</span></li> <li><span class="nowrap"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734"><span class="monospaced">U+1D709</span> </span><span style="font-size:125%;line-height:1em">𝜉</span> <span style="font-variant: small-caps; text-transform: lowercase;">MATHEMATICAL ITALIC SMALL XI</span></li> <li><span class="nowrap"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734"><span class="monospaced">U+1D729</span> </span><span style="font-size:125%;line-height:1em">𝜩</span> <span style="font-variant: small-caps; text-transform: lowercase;">MATHEMATICAL BOLD ITALIC CAPITAL XI</span></li> <li><span class="nowrap"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734"><span class="monospaced">U+1D743</span> </span><span style="font-size:125%;line-height:1em">𝝃</span> <span style="font-variant: small-caps; text-transform: lowercase;">MATHEMATICAL BOLD ITALIC SMALL XI</span></li> <li><span class="nowrap"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734"><span class="monospaced">U+1D763</span> </span><span style="font-size:125%;line-height:1em">𝝣</span> <span style="font-variant: small-caps; text-transform: lowercase;">MATHEMATICAL SANS-SERIF BOLD CAPITAL XI</span></li> <li><span class="nowrap"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734"><span class="monospaced">U+1D77D</span> </span><span style="font-size:125%;line-height:1em">𝝽</span> <span style="font-variant: small-caps; text-transform: lowercase;">MATHEMATICAL SANS-SERIF BOLD SMALL XI</span></li> <li><span class="nowrap"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734"><span class="monospaced">U+1D79D</span> </span><span style="font-size:125%;line-height:1em">𝞝</span> <span style="font-variant: small-caps; text-transform: lowercase;">MATHEMATICAL SANS-SERIF BOLD ITALIC CAPITAL XI</span></li> <li><span class="nowrap"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734"><span class="monospaced">U+1D7B7</span> </span><span style="font-size:125%;line-height:1em">𝞷</span> <span style="font-variant: small-caps; text-transform: lowercase;">MATHEMATICAL SANS-SERIF BOLD ITALIC SMALL XI</span></li></ul> <div class="mw-heading mw-heading2"><h2 id="References">References</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Xi_(letter)&action=edit&section=14" title="Edit section: References"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <div class="mw-references-wrap"><ol class="references"> <li id="cite_note-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-1">^</a></b></span> <span class="reference-text"><style data-mw-deduplicate="TemplateStyles:r1238218222">.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/6/65/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/d/d6/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/a/aa/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/4/4c/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}</style><cite id="CITEREFReference-OED-xi" class="citation encyclopaedia cs1"><span class="id-lock-subscription" title="Paid subscription required"><a rel="nofollow" class="external text" href="https://www.oed.com/search/dictionary/?q=xi">"xi"</a></span>. <i><a href="/wiki/Oxford_English_Dictionary" title="Oxford English Dictionary">Oxford English Dictionary</a></i> (Online ed.). <a href="/wiki/Oxford_University_Press" title="Oxford University Press">Oxford University Press</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=bookitem&rft.atitle=xi&rft.btitle=Oxford+English+Dictionary&rft.edition=Online&rft.pub=Oxford+University+Press&rft_id=https%3A%2F%2Fwww.oed.com%2Fsearch%2Fdictionary%2F%3Fq%3Dxi&rfr_id=info%3Asid%2Fen.wikipedia.org%3AXi+%28letter%29" class="Z3988"></span> <span style="font-size:0.95em; font-size:95%; color: var( --color-subtle, #555 )">(Subscription or <a rel="nofollow" class="external text" href="https://www.oed.com/public/login/loggingin#withyourlibrary">participating institution membership</a> required.)</span></span> </li> <li id="cite_note-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-2">^</a></b></span> <span class="reference-text">"xi". <i>New Oxford American Dictionary</i>, 2nd Edition.</span> </li> <li id="cite_note-3"><span class="mw-cite-backlink"><b><a href="#cite_ref-3">^</a></b></span> <span class="reference-text">SPIE Optipedia article: <a rel="nofollow" class="external text" href="http://spie.org/x34301.xml">"Spatial Frequency"</a></span> </li> <li id="cite_note-4"><span class="mw-cite-backlink"><b><a href="#cite_ref-4">^</a></b></span> <span class="reference-text">IUPAC Gold Book Entry: <a rel="nofollow" class="external text" href="http://goldbook.iupac.org/E02283.html">"Extent of Reaction"</a> <a rel="nofollow" class="external text" href="https://web.archive.org/web/20120629101118/http://goldbook.iupac.org/E02283.html">Archived</a> June 29, 2012, at the <a href="/wiki/Wayback_Machine" title="Wayback Machine">Wayback Machine</a></span> </li> <li id="cite_note-BuckinghamCooper2015-5"><span class="mw-cite-backlink"><b><a href="#cite_ref-BuckinghamCooper2015_5-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFBuckinghamCooperPurchase2015" class="citation book cs1">Buckingham, John; Cooper, Caroline M.; Purchase, Rupert (18 November 2015). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=n4zwCgAAQBAJ&pg=PA53"><i>Natural Products Desk Reference</i></a>. CRC Press. pp. 53–. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-1-4398-7362-5" title="Special:BookSources/978-1-4398-7362-5"><bdi>978-1-4398-7362-5</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Natural+Products+Desk+Reference&rft.pages=53-&rft.pub=CRC+Press&rft.date=2015-11-18&rft.isbn=978-1-4398-7362-5&rft.aulast=Buckingham&rft.aufirst=John&rft.au=Cooper%2C+Caroline+M.&rft.au=Purchase%2C+Rupert&rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3Dn4zwCgAAQBAJ%26pg%3DPA53&rfr_id=info%3Asid%2Fen.wikipedia.org%3AXi+%28letter%29" class="Z3988"></span></span> </li> <li id="cite_note-6"><span class="mw-cite-backlink"><b><a href="#cite_ref-6">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation book cs1"><a rel="nofollow" class="external text" href="https://books.google.com/books?id=4USgAgAAQBAJ&pg=1160"><i>Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names</i></a>. 2014. pp. 1159–1160. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/9780854041824" title="Special:BookSources/9780854041824"><bdi>9780854041824</bdi></a><span class="reference-accessdate">. Retrieved <span class="nowrap">11 September</span> 2017</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Nomenclature+of+Organic+Chemistry%3A+IUPAC+Recommendations+and+Preferred+Names&rft.pages=1159-1160&rft.date=2014&rft.isbn=9780854041824&rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3D4USgAgAAQBAJ%26pg%3D1160&rfr_id=info%3Asid%2Fen.wikipedia.org%3AXi+%28letter%29" class="Z3988"></span></span> </li> </ol></div> <div class="mw-heading mw-heading2"><h2 id="External_links">External links</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Xi_(letter)&action=edit&section=15" title="Edit section: External links"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1235681985">.mw-parser-output .side-box{margin:4px 0;box-sizing:border-box;border:1px solid #aaa;font-size:88%;line-height:1.25em;background-color:var(--background-color-interactive-subtle,#f8f9fa);display:flow-root}.mw-parser-output .side-box-abovebelow,.mw-parser-output .side-box-text{padding:0.25em 0.9em}.mw-parser-output .side-box-image{padding:2px 0 2px 0.9em;text-align:center}.mw-parser-output .side-box-imageright{padding:2px 0.9em 2px 0;text-align:center}@media(min-width:500px){.mw-parser-output .side-box-flex{display:flex;align-items:center}.mw-parser-output .side-box-text{flex:1;min-width:0}}@media(min-width:720px){.mw-parser-output .side-box{width:238px}.mw-parser-output .side-box-right{clear:right;float:right;margin-left:1em}.mw-parser-output .side-box-left{margin-right:1em}}</style><style data-mw-deduplicate="TemplateStyles:r1237033735">@media print{body.ns-0 .mw-parser-output .sistersitebox{display:none!important}}@media screen{html.skin-theme-clientpref-night .mw-parser-output .sistersitebox img[src*="Wiktionary-logo-en-v2.svg"]{background-color:white}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .sistersitebox img[src*="Wiktionary-logo-en-v2.svg"]{background-color:white}}</style><div class="side-box side-box-right plainlinks sistersitebox"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1126788409"> <div class="side-box-flex"> <div class="side-box-image"><span class="noviewer" typeof="mw:File"><span><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/9/99/Wiktionary-logo-en-v2.svg/40px-Wiktionary-logo-en-v2.svg.png" decoding="async" width="40" height="40" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/9/99/Wiktionary-logo-en-v2.svg/60px-Wiktionary-logo-en-v2.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/9/99/Wiktionary-logo-en-v2.svg/80px-Wiktionary-logo-en-v2.svg.png 2x" data-file-width="512" data-file-height="512" /></span></span></div> <div class="side-box-text plainlist">Look up <i><b><a href="https://en.wiktionary.org/wiki/%CE%9E" class="extiw" title="wiktionary:Ξ">Ξ</a></b></i> or <i><b><a href="https://en.wiktionary.org/wiki/%CE%BE" class="extiw" title="wiktionary:ξ">ξ</a></b></i> in Wiktionary, the free dictionary.</div></div> </div> <ul><li><span class="noviewer" typeof="mw:File"><a href="/wiki/File:Commons-logo.svg" class="mw-file-description"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/12px-Commons-logo.svg.png" decoding="async" width="12" height="16" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/18px-Commons-logo.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/24px-Commons-logo.svg.png 2x" data-file-width="1024" data-file-height="1376" /></a></span> Media related to <a href="https://commons.wikimedia.org/wiki/Category:Xi_(letter)" class="extiw" title="commons:Category:Xi (letter)">Xi (letter)</a> at Wikimedia Commons</li></ul>    </div><noscript><img src="https://login.wikimedia.org/wiki/Special:CentralAutoLogin/start?type=1x1" alt="" width="1" height="1" style="border: none; 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