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class="vector-toc-link" href="#Notes"> <div class="vector-toc-text"> <span class="vector-toc-numb">5</span> <span>Notes</span> </div> </a> <ul id="toc-Notes-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> </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" title="Table of Contents" > <input type="checkbox" id="vector-page-titlebar-toc-checkbox" role="button" aria-haspopup="true" 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Available in 86 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-86" 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">86 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/Tau" title="Tau – Afrikaans" lang="af" hreflang="af" data-title="Tau" 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%A4" title="Τ – Alemannic" lang="gsw" hreflang="gsw" data-title="Τ" 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%A4" title="Τ – Abkhazian" lang="ab" hreflang="ab" data-title="Τ" 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/%D8%AA%D8%A7%D9%88" title="تاو – Arabic" lang="ar" hreflang="ar" data-title="تاو" 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%A4" title="Τ – Aramaic" lang="arc" hreflang="arc" data-title="Τ" 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%9F%E0%A6%BE%E0%A6%89" title="টাউ – Bangla" lang="bn" hreflang="bn" data-title="টাউ" 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%A4" title="Τ – Minnan" lang="nan" hreflang="nan" data-title="Τ" 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%A2%D0%B0%D1%83" title="Тау – Belarusian" lang="be" hreflang="be" data-title="Тау" 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%A2%D0%B0%D1%9E_(%D0%BB%D1%96%D1%82%D0%B0%D1%80%D0%B0)" title="Таў (літара) – Belarusian (Taraškievica orthography)" lang="be-tarask" hreflang="be-tarask" data-title="Таў (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%A2%D0%B0%D1%83" title="Тау – Bulgarian" lang="bg" hreflang="bg" data-title="Тау" 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/Tau_(Buchstabe)" title="Tau (Buchstabe) – Bavarian" lang="bar" hreflang="bar" data-title="Tau (Buchstabe)" 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%90%E0%BD%BC%E0%BC%8D" title="ཐོ། – Tibetan" lang="bo" hreflang="bo" data-title="ཐོ།" 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-bs mw-list-item"><a href="https://bs.wikipedia.org/wiki/Tau" title="Tau – Bosnian" lang="bs" hreflang="bs" data-title="Tau" data-language-autonym="Bosanski" data-language-local-name="Bosnian" class="interlanguage-link-target"><span>Bosanski</span></a></li><li class="interlanguage-link interwiki-br mw-list-item"><a href="https://br.wikipedia.org/wiki/Tau_(lizherenn)" title="Tau (lizherenn) – Breton" lang="br" hreflang="br" data-title="Tau (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/Tau_(lletra_grega)" title="Tau (lletra grega) – Catalan" lang="ca" hreflang="ca" data-title="Tau (lletra grega)" 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/Tau_(p%C3%ADsmeno)" title="Tau (písmeno) – Czech" lang="cs" hreflang="cs" data-title="Tau (písmeno)" 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/Tau_(llythyren)" title="Tau (llythyren) – Welsh" lang="cy" hreflang="cy" data-title="Tau (llythyren)" 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/Tau_(bogstav)" title="Tau (bogstav) – Danish" lang="da" hreflang="da" data-title="Tau (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%A4" title="Τ – Northern Sami" lang="se" hreflang="se" data-title="Τ" 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/Tau_(Buchstabe)" title="Tau (Buchstabe) – German" lang="de" hreflang="de" data-title="Tau (Buchstabe)" 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/Tau" title="Tau – Estonian" lang="et" hreflang="et" data-title="Tau" 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%A4%CE%B1%CF%85" title="Ταυ – Greek" lang="el" hreflang="el" data-title="Ταυ" 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%A4" title="Τ – Spanish" lang="es" hreflang="es" data-title="Τ" 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/Ta%C5%ADo_(litero)" title="Taŭo (litero) – Esperanto" lang="eo" hreflang="eo" data-title="Taŭo (litero)" 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/Tau_(hizkia)" title="Tau (hizkia) – Basque" lang="eu" hreflang="eu" data-title="Tau (hizkia)" 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/%D8%AA%D8%A7%D9%88" title="تاو – Persian" lang="fa" hreflang="fa" data-title="تاو" 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/Tau" title="Tau – French" lang="fr" hreflang="fr" data-title="Tau" 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/T%C3%B3" title="Tó – Irish" lang="ga" hreflang="ga" data-title="Tó" 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/Tau" title="Tau – Scottish Gaelic" lang="gd" hreflang="gd" data-title="Tau" 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/Tau" title="Tau – Galician" lang="gl" hreflang="gl" data-title="Tau" 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%A4" title="Τ – Hakka Chinese" lang="hak" hreflang="hak" data-title="Τ" 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%A4" title="Τ – Korean" lang="ko" hreflang="ko" data-title="Τ" data-language-autonym="한국어" data-language-local-name="Korean" class="interlanguage-link-target"><span>한국어</span></a></li><li class="interlanguage-link interwiki-ha mw-list-item"><a href="https://ha.wikipedia.org/wiki/Tau" title="Tau – Hausa" lang="ha" hreflang="ha" data-title="Tau" data-language-autonym="Hausa" data-language-local-name="Hausa" class="interlanguage-link-target"><span>Hausa</span></a></li><li class="interlanguage-link interwiki-hy mw-list-item"><a href="https://hy.wikipedia.org/wiki/%D5%8F%D5%A1%D5%B8%D6%82_(%D5%BF%D5%A1%D5%BC)" title="Տաու (տառ) – Armenian" lang="hy" hreflang="hy" data-title="Տաու (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/Tau" title="Tau – Croatian" lang="hr" hreflang="hr" data-title="Tau" 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/Tau" title="Tau – Indonesian" lang="id" hreflang="id" data-title="Tau" 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/T%C3%A1_(b%C3%B3kstafur)" title="Tá (bókstafur) – Icelandic" lang="is" hreflang="is" data-title="Tá (bókstafur)" 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/Tau" title="Tau – Italian" lang="it" hreflang="it" data-title="Tau" 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%98%D7%90%D7%95_(%D7%90%D7%95%D7%AA)" title="טאו (אות) – Hebrew" lang="he" hreflang="he" data-title="טאו (אות)" 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%A2%E1%83%90%E1%83%A3_(%E1%83%90%E1%83%A1%E1%83%9D)" title="ტაუ (ასო) – Georgian" lang="ka" hreflang="ka" data-title="ტაუ (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/Tau" title="Tau – Swahili" lang="sw" hreflang="sw" data-title="Tau" 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%A2%D0%B0%D1%83" title="Тау – Komi" lang="kv" hreflang="kv" data-title="Тау" 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%A4" title="Τ – Haitian Creole" lang="ht" hreflang="ht" data-title="Τ" 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/Tau" title="Tau – Kurdish" lang="ku" hreflang="ku" data-title="Tau" 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/Tau" title="Tau – Latin" lang="la" hreflang="la" data-title="Tau" 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/Tau_(burts)" title="Tau (burts) – Latvian" lang="lv" hreflang="lv" data-title="Tau (burts)" 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/Tau" title="Tau – Luxembourgish" lang="lb" hreflang="lb" data-title="Tau" 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%A2%D0%B0%D1%83" title="Тау – Lezghian" lang="lez" hreflang="lez" data-title="Тау" 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/Tau_(raid%C4%97)" title="Tau (raidė) – Lithuanian" lang="lt" hreflang="lt" data-title="Tau (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/Tau" title="Tau – Hungarian" lang="hu" hreflang="hu" data-title="Tau" data-language-autonym="Magyar" data-language-local-name="Hungarian" class="interlanguage-link-target"><span>Magyar</span></a></li><li class="interlanguage-link interwiki-ml mw-list-item"><a href="https://ml.wikipedia.org/wiki/%E0%B4%B1%E0%B5%8D%E0%B4%B1%E0%B5%97" title="റ്റൗ – Malayalam" lang="ml" hreflang="ml" data-title="റ്റൗ" data-language-autonym="മലയാളം" data-language-local-name="Malayalam" class="interlanguage-link-target"><span>മലയാളം</span></a></li><li class="interlanguage-link interwiki-mr mw-list-item"><a href="https://mr.wikipedia.org/wiki/%E0%A4%9F%E0%A4%BE%E0%A4%89" title="टाउ – Marathi" lang="mr" hreflang="mr" data-title="टाउ" 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/Tau" title="Tau – Malay" lang="ms" hreflang="ms" data-title="Tau" 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/Tau" title="Tau – Mindong" lang="cdo" hreflang="cdo" data-title="Tau" 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%A4" title="Τ – Nahuatl" lang="nah" hreflang="nah" data-title="Τ" 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/Tau_(letter)" title="Tau (letter) – Dutch" lang="nl" hreflang="nl" data-title="Tau (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%A4" title="Τ – Japanese" lang="ja" hreflang="ja" data-title="Τ" 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/Tau_(bokstav)" title="Tau (bokstav) – Norwegian Bokmål" lang="nb" hreflang="nb" data-title="Tau (bokstav)" 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/Bokstaven_tau" title="Bokstaven tau – Norwegian Nynorsk" lang="nn" hreflang="nn" data-title="Bokstaven tau" 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/Tau" title="Tau – Occitan" lang="oc" hreflang="oc" data-title="Tau" 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%9F%E0%A8%BE%E0%A8%93" title="ਟਾਓ – Punjabi" lang="pa" hreflang="pa" data-title="ਟਾਓ" 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/Tau" title="Tau – Low German" lang="nds" hreflang="nds" data-title="Tau" 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/Tau" title="Tau – Polish" lang="pl" hreflang="pl" data-title="Tau" 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%A4" title="Τ – Portuguese" lang="pt" hreflang="pt" data-title="Τ" 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/Tau" title="Tau – Romanian" lang="ro" hreflang="ro" data-title="Tau" 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%A2%D0%B0%D1%83" title="Тау – Russian" lang="ru" hreflang="ru" data-title="Тау" 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/Tau" title="Tau – Simple English" lang="en-simple" hreflang="en-simple" data-title="Tau" 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/Tau" title="Tau – Slovak" lang="sk" hreflang="sk" data-title="Tau" 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/Tau" title="Tau – Slovenian" lang="sl" hreflang="sl" data-title="Tau" 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/%D8%AA%D8%A7%D9%88" title="تاو – Central Kurdish" lang="ckb" hreflang="ckb" data-title="تاو" 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%A2%D0%B0%D1%83_(%D1%81%D0%BB%D0%BE%D0%B2%D0%BE)" title="Тау (слово) – Serbian" lang="sr" hreflang="sr" data-title="Тау (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/Tau" title="Tau – Serbo-Croatian" lang="sh" hreflang="sh" data-title="Tau" 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/Tau" title="Tau – Finnish" lang="fi" hreflang="fi" data-title="Tau" 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/Tau_(bokstav)" title="Tau (bokstav) – Swedish" lang="sv" hreflang="sv" data-title="Tau (bokstav)" data-language-autonym="Svenska" data-language-local-name="Swedish" class="interlanguage-link-target"><span>Svenska</span></a></li><li class="interlanguage-link interwiki-tl badge-Q70893996 mw-list-item" title=""><a href="https://tl.wikipedia.org/wiki/Tau" title="Tau – Tagalog" lang="tl" hreflang="tl" data-title="Tau" data-language-autonym="Tagalog" data-language-local-name="Tagalog" class="interlanguage-link-target"><span>Tagalog</span></a></li><li class="interlanguage-link interwiki-th mw-list-item"><a href="https://th.wikipedia.org/wiki/%E0%B9%80%E0%B8%97%E0%B8%B2_(%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="เทา (อักษรกรีก) – Thai" lang="th" hreflang="th" data-title="เทา (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/Taf" title="Taf – Turkish" lang="tr" hreflang="tr" data-title="Taf" 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%A2%D0%B0%D1%83_(%D0%BB%D1%96%D1%82%D0%B5%D1%80%D0%B0)" title="Тау (літера) – Ukrainian" lang="uk" hreflang="uk" data-title="Тау (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/Tau" title="Tau – Veps" lang="vep" hreflang="vep" data-title="Tau" 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/Tau" title="Tau – Vietnamese" lang="vi" hreflang="vi" data-title="Tau" 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/Tau" title="Tau – Waray" lang="war" hreflang="war" data-title="Tau" 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%A4" title="Τ – Wu" lang="wuu" hreflang="wuu" data-title="Τ" 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%A4" title="Τ – Cantonese" lang="yue" hreflang="yue" data-title="Τ" 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%A4" title="Τ – Dimli" lang="diq" hreflang="diq" data-title="Τ" data-language-autonym="Zazaki" data-language-local-name="Dimli" 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%A4" title="Τ – Chinese" lang="zh" hreflang="zh" data-title="Τ" 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%A4" title="Τ – Komering" lang="kge" hreflang="kge" data-title="Τ" 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class="mw-body-content"><div class="mw-content-ltr mw-parser-output" lang="en" dir="ltr"><div class="shortdescription nomobile noexcerpt noprint searchaux" style="display:none">Nineteenth letter in the Greek alphabet</div> <style data-mw-deduplicate="TemplateStyles:r1236090951">.mw-parser-output .hatnote{font-style:italic}.mw-parser-output div.hatnote{padding-left:1.6em;margin-bottom:0.5em}.mw-parser-output .hatnote i{font-style:normal}.mw-parser-output .hatnote+link+.hatnote{margin-top:-0.5em}@media print{body.ns-0 .mw-parser-output .hatnote{display:none!important}}</style><div role="note" class="hatnote navigation-not-searchable">This article is about the letter of the Greek alphabet. For the mathematical constant, see <a href="/wiki/Tau_(mathematical_constant)" class="mw-redirect" title="Tau (mathematical constant)">Tau (mathematical constant)</a>. For other uses, see <a href="/wiki/Tau_(disambiguation)" class="mw-disambig" title="Tau (disambiguation)">Tau (disambiguation)</a>.</div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951" /><div role="note" class="hatnote navigation-not-searchable">Not to be confused with <a href="/wiki/Tao" title="Tao">Tao</a> or the Latin letter <a href="/wiki/T" title="T">T</a>.</div> <style data-mw-deduplicate="TemplateStyles:r1129693374">.mw-parser-output .hlist dl,.mw-parser-output .hlist ol,.mw-parser-output .hlist ul{margin:0;padding:0}.mw-parser-output .hlist dd,.mw-parser-output .hlist dt,.mw-parser-output .hlist li{margin:0;display:inline}.mw-parser-output .hlist.inline,.mw-parser-output .hlist.inline dl,.mw-parser-output .hlist.inline ol,.mw-parser-output .hlist.inline ul,.mw-parser-output .hlist dl dl,.mw-parser-output .hlist dl ol,.mw-parser-output .hlist dl ul,.mw-parser-output .hlist ol dl,.mw-parser-output .hlist ol ol,.mw-parser-output .hlist ol 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#aaa;line-height:1.6em;font-weight:bold;padding-bottom:0.4em;border-bottom:1px solid #aaa}</style><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" /><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:Tau_uc_lc.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/4/4a/Tau_uc_lc.svg/100px-Tau_uc_lc.svg.png" decoding="async" width="100" height="67" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/4/4a/Tau_uc_lc.svg/150px-Tau_uc_lc.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/4/4a/Tau_uc_lc.svg/200px-Tau_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 href="/wiki/Xi_(letter)" title="Xi (letter)">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 class="mw-selflink selflink">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> Ϝϝ</td><td style="padding-right:1.0em;"> <a href="/wiki/Digamma" title="Digamma">Digamma</a></td><td> Ͱͱ</td><td style="padding-right:0.6em;"> <a href="/wiki/Heta" title="Heta">Heta</a></td></tr><tr style="vertical-align:top"><td> Ϻϻ</td><td style="padding-right:1.0em;"> <a href="/wiki/San_(letter)" title="San (letter)">San</a></td><td> Ϙϙ</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> Ͷͷ</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> Ͳͳ</td><td style="padding-right:0.6em;"> <a href="/wiki/Sampi" title="Sampi">Sampi</a></td></tr><tr style="vertical-align:top"><td>Ϸϸ</td><td style="padding-right:1.0em;"> <a href="/wiki/Sho_(letter)" title="Sho (letter)">Sho</a></td><td></td><td style="padding-right:0.6em;"></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/Ou_(ligature)" title="Ou (ligature)">ȢȢ</a></li><li style="font-size:110%;"><a href="/wiki/Kai_(conjunction)" title="Kai (conjunction)">Ϗϗ</a></li><li style="font-size:110%;"><a href="/wiki/Stigma_(ligature)" title="Stigma (ligature)">Ϛϛ</a></li><li style="font-size:110%;"><a href="/wiki/Staurogram" title="Staurogram">⳨</a></li><li style="font-size:110%;"><a href="/wiki/Chi_Rho" title="Chi Rho">☧</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>Tau</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="/ˈ/: primary stress follows">ˈ</span><span title="'t' in 'tie'">t</span><span title="/aʊ/: 'ou' in 'mouth'">aʊ</span></span>,<span class="wrap"> </span><span style="border-bottom:1px dotted"><span title="/ˈ/: primary stress follows">ˈ</span><span title="'t' in 'tie'">t</span><span title="/ɔː/: 'au' in 'fraud'">ɔː</span></span>,<span class="wrap"> </span><span style="border-bottom:1px dotted"><span title="/ˈ/: primary stress follows">ˈ</span><span title="'t' in 'tie'">t</span><span title="/ɒ/: 'o' in 'body'">ɒ</span></span>/</a></span></span>;<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> uppercase <b>Τ</b>, lowercase <b>τ</b> or <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\boldsymbol {\tau }}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mrow class="MJX-TeXAtom-ORD"> <mi mathvariant="bold-italic">τ</mi> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle {\boldsymbol {\tau }}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/beb1359149db88a28c86f0a3030894b71610a224" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.418ex; height:1.676ex;" alt="{\displaystyle {\boldsymbol {\tau }}}" /></span>; <a href="/wiki/Greek_language" title="Greek language">Greek</a>: <span lang="el">ταυ</span> <span class="IPA nowrap" lang="el-Latn-fonipa"><a href="/wiki/Help:IPA/Greek" title="Help:IPA/Greek">[taf]</a></span>) is the nineteenth letter of the <a href="/wiki/Greek_alphabet" title="Greek alphabet">Greek alphabet</a>, representing the <a href="/wiki/Voiceless_alveolar_plosive" class="mw-redirect" title="Voiceless alveolar plosive">voiceless dental or alveolar plosive</a> <style data-mw-deduplicate="TemplateStyles:r1177148991">.mw-parser-output .IPA-label-small{font-size:85%}.mw-parser-output .references .IPA-label-small,.mw-parser-output .infobox .IPA-label-small,.mw-parser-output .navbox .IPA-label-small{font-size:100%}</style><span class="IPA-label IPA-label-small">IPA:</span> <span class="IPA nowrap" lang="el-Latn-fonipa"><a href="/wiki/Help:IPA/Greek" title="Help:IPA/Greek">[t]</a></span>. In the system of <a href="/wiki/Greek_numerals" title="Greek numerals">Greek numerals</a>, it has a value of 300. </p><p>The name in English is pronounced <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="'t' in 'tie'">t</span><span title="/aʊ/: 'ou' in 'mouth'">aʊ</span></span>/</a></span></span> 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="'t' in 'tie'">t</span><span title="/ɔː/: 'au' in 'fraud'">ɔː</span></span>/</a></span></span>,<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> but in <a href="/wiki/Modern_Greek" title="Modern Greek">Greek</a> it is <span class="IPA nowrap" lang="el-Latn-fonipa"><a href="/wiki/Help:IPA/Greek" title="Help:IPA/Greek">[taf]</a></span>.<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><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> This is because the pronunciation of the combination of Greek letters αυ can have the pronunciation of either <span class="IPA nowrap" lang="und-Latn-fonipa" title="Representation in the International Phonetic Alphabet (IPA)">[ai]</span>, <span class="IPA nowrap" lang="und-Latn-fonipa" title="Representation in the International Phonetic Alphabet (IPA)">[av]</span> or <span class="IPA nowrap" lang="und-Latn-fonipa" title="Representation in the International Phonetic Alphabet (IPA)">[af]</span>, depending on what follows and if a <a href="/wiki/Diaeresis_(diacritic)" title="Diaeresis (diacritic)">diaeresis</a> is present on the second vowel (see <a href="/wiki/Greek_orthography" title="Greek orthography">Greek orthography</a>). </p><p>Tau was derived from the <a href="/wiki/Phoenician_alphabet" title="Phoenician alphabet">Phoenician letter</a> <a href="/wiki/Taw" title="Taw">taw</a> <span typeof="mw:File"><a href="/wiki/File:Phoenician_taw.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/5/59/Phoenician_taw.svg/20px-Phoenician_taw.svg.png" decoding="async" width="20" height="20" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/5/59/Phoenician_taw.svg/30px-Phoenician_taw.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/5/59/Phoenician_taw.svg/40px-Phoenician_taw.svg.png 2x" data-file-width="85" data-file-height="85" /></a></span> (𐤕).<sup id="cite_ref-5" class="reference"><a href="#cite_note-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> Letters that arose from tau include Roman <a href="/wiki/T" title="T">T</a> and Cyrillic <a href="/wiki/Te_(Cyrillic)" title="Te (Cyrillic)">Te</a> (Т, т). </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="Modern_usage">Modern usage</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Tau&action=edit&section=1" title="Edit section: Modern usage"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951" /><div role="note" class="hatnote navigation-not-searchable">See also: <a href="/wiki/Greek_letters_used_in_mathematics,_science,_and_engineering#Ττ_(tau)" title="Greek letters used in mathematics, science, and engineering">Greek letters used in mathematics, science, and engineering § Ττ (tau)</a></div> <p>The lower-case letter τ is used as a symbol for: </p> <ul><li><a href="/wiki/Per_unit_tax" title="Per unit tax">Specific tax</a> amount<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></ul> <div class="mw-heading mw-heading3"><h3 id="Biology">Biology</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Tau&action=edit&section=2" title="Edit section: Biology"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li>The expressed period of the <a href="/wiki/Free-running_sleep" title="Free-running sleep">freerunning</a> rhythm of an animal, i.e., the length of the daily cycle of an animal when kept in constant light or constant darkness</li> <li>The dose interval in <a href="/wiki/Pharmacokinetics" title="Pharmacokinetics">pharmacokinetics</a><sup id="cite_ref-7" class="reference"><a href="#cite_note-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup></li> <li>The core variable in <a href="/wiki/General_tau_theory" title="General tau theory">general tau theory</a></li> <li><a href="/wiki/Tau_(protein)" class="mw-redirect" title="Tau (protein)">Tau</a> in biochemistry, a protein associated with <a href="/wiki/Microtubule" title="Microtubule">microtubules</a> and implicated in neurodegenerative diseases such as <a href="/wiki/Alzheimer%27s_disease" title="Alzheimer's disease">Alzheimer's disease</a>, some forms of <a href="/wiki/Frontotemporal_lobar_degeneration" title="Frontotemporal lobar degeneration">frontotemporal lobar degeneration</a>, and <a href="/wiki/Chronic_traumatic_encephalopathy" title="Chronic traumatic encephalopathy">chronic traumatic encephalopathy</a><sup id="cite_ref-8" class="reference"><a href="#cite_note-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-9" class="reference"><a href="#cite_note-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup></li></ul> <div class="mw-heading mw-heading3"><h3 id="Mathematics">Mathematics</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Tau&action=edit&section=3" title="Edit section: Mathematics"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/Divisor_function" title="Divisor function">Divisor function</a> in number theory, also denoted <i>d</i> or σ<sub>0</sub><sup id="cite_ref-10" class="reference"><a href="#cite_note-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-:0_11-0" class="reference"><a href="#cite_note-:0-11"><span class="cite-bracket">[</span>note 1<span class="cite-bracket">]</span></a></sup></li> <li><a href="/wiki/Ramanujan_tau_function" title="Ramanujan tau function">Ramanujan tau function</a><sup id="cite_ref-12" class="reference"><a href="#cite_note-12"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-13" class="reference"><a href="#cite_note-13"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup></li> <li><a href="/wiki/Golden_ratio" title="Golden ratio">Golden ratio</a> (1.618...), although φ (<a href="/wiki/Phi" title="Phi">phi</a>) is more common<sup id="cite_ref-14" class="reference"><a href="#cite_note-14"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-:0_11-1" class="reference"><a href="#cite_note-:0-11"><span class="cite-bracket">[</span>note 1<span class="cite-bracket">]</span></a></sup></li> <li><a href="/wiki/Kendall_tau_rank_correlation_coefficient" class="mw-redirect" title="Kendall tau rank correlation coefficient">Kendall tau rank correlation coefficient</a> in statistics<sup id="cite_ref-15" class="reference"><a href="#cite_note-15"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup></li> <li><a href="/wiki/Stopping_time" title="Stopping time">Stopping time</a> in stochastic processes.<sup id="cite_ref-16" class="reference"><a href="#cite_note-16"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-:1_17-0" class="reference"><a href="#cite_note-:1-17"><span class="cite-bracket">[</span>note 2<span class="cite-bracket">]</span></a></sup></li> <li><a href="/wiki/Tau_(mathematical_constant)" class="mw-redirect" title="Tau (mathematical constant)">Tau</a>, the ratio of the circumference to the radius of a circle, which is equal to 2<a href="/wiki/Pi" title="Pi"><span class="texhtml mvar" style="font-style:italic;">π</span></a> (6.28318...)<sup id="cite_ref-18" class="reference"><a href="#cite_note-18"><span class="cite-bracket">[</span>16<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-19" class="reference"><a href="#cite_note-19"><span class="cite-bracket">[</span>17<span class="cite-bracket">]</span></a></sup></li> <li><a href="/wiki/Tau_function_(disambiguation)" class="mw-redirect mw-disambig" title="Tau function (disambiguation)">Tau functions</a>, several</li> <li><a href="/wiki/Torsion_of_a_curve" title="Torsion of a curve">Torsion of a curve</a> in differential geometry<sup id="cite_ref-20" class="reference"><a href="#cite_note-20"><span class="cite-bracket">[</span>18<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-:0_11-2" class="reference"><a href="#cite_note-:0-11"><span class="cite-bracket">[</span>note 1<span class="cite-bracket">]</span></a></sup></li> <li><a href="/wiki/Translation_(geometry)" title="Translation (geometry)">Translation</a> in Euclidean geometry (although the Latin letter <a href="/wiki/T" title="T">T</a> is used more often)</li> <li>The <a href="/wiki/Prouhet%E2%80%93Thue%E2%80%93Morse_constant" title="Prouhet–Thue–Morse constant">Prouhet–Thue–Morse constant</a><sup id="cite_ref-21" class="reference"><a href="#cite_note-21"><span class="cite-bracket">[</span>19<span class="cite-bracket">]</span></a></sup></li></ul> <div class="mw-heading mw-heading3"><h3 id="Physics">Physics</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Tau&action=edit&section=4" title="Edit section: Physics"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/Proper_time" title="Proper time">Proper time</a> in relativity</li> <li><a href="/wiki/Shear_stress" title="Shear stress">Shear stress</a> in continuum mechanics<sup id="cite_ref-22" class="reference"><a href="#cite_note-22"><span class="cite-bracket">[</span>20<span class="cite-bracket">]</span></a></sup></li> <li>The lifetime of a <a href="/wiki/Spontaneous_emission" title="Spontaneous emission">spontaneous emission</a> process</li> <li><a href="/wiki/Tau_(particle)" title="Tau (particle)">Tau</a>, an elementary particle in particle physics</li> <li>Tau in <a href="/wiki/Astronomy" title="Astronomy">astronomy</a> is a measure of <a href="/wiki/Optical_depth" title="Optical depth">optical depth</a>, or how much sunlight cannot penetrate the atmosphere</li> <li>In the physical sciences, tau is sometimes used as <a href="/wiki/Time" title="Time">time</a> variable, to avoid confusing t as temperature</li> <li><a href="/wiki/Time_constant" title="Time constant">Time constant</a> (also <a href="/wiki/Relaxation_time" class="mw-redirect" title="Relaxation time">relaxation time</a>) of any system, such as an <a href="/wiki/RC_circuit" title="RC circuit">RC circuit</a><sup id="cite_ref-23" class="reference"><a href="#cite_note-23"><span class="cite-bracket">[</span>21<span class="cite-bracket">]</span></a></sup></li> <li><a href="/wiki/Torque" title="Torque">Torque</a>, the rotational force in mechanics<sup id="cite_ref-24" class="reference"><a href="#cite_note-24"><span class="cite-bracket">[</span>22<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-25" class="reference"><a href="#cite_note-25"><span class="cite-bracket">[</span>23<span class="cite-bracket">]</span></a></sup></li> <li>The symbol for <a href="/wiki/Tortuosity" title="Tortuosity">tortuosity</a> in hydrogeology</li> <li>In thermal physics, the symbol for the fundamental temperature <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \tau =k_{B}T}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>τ</mi> <mo>=</mo> <msub> <mi>k</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>B</mi> </mrow> </msub> <mi>T</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \tau =k_{B}T}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/2d3493934a5ed0d5921957451e8017c8b8b0572c" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:8.627ex; height:2.509ex;" alt="{\displaystyle \tau =k_{B}T}" /></span></li></ul> <div class="mw-heading mw-heading2"><h2 id="Symbolism">Symbolism</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Tau&action=edit&section=5" title="Edit section: Symbolism"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li>In ancient times, tau was used as a symbol for <a href="/wiki/Life" title="Life">life</a> or <a href="/wiki/Resurrection" title="Resurrection">resurrection</a>, whereas the eighth letter of the Greek alphabet, <a href="/wiki/Theta" title="Theta">theta</a>, was considered the symbol of <a href="/wiki/Death" title="Death">death</a>.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (January 2024)">citation needed</span></a></i>]</sup></li> <li>In Biblical times, the <a href="/wiki/Taw" title="Taw">taw</a> was put on men to distinguish those who lamented sin, although newer versions of the Bible have replaced the ancient term <i>taw</i> with <i>mark</i> (Ezekiel 9:4) or <i>signature</i> (Job 31:35). Its original sound value is a <a href="/wiki/Voiceless_alveolar_plosive" class="mw-redirect" title="Voiceless alveolar plosive">voiceless alveolar plosive</a>, IPA /t/<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (January 2024)">citation needed</span></a></i>]</sup></li> <li>The symbolism of the <a href="/wiki/Cross" title="Cross">cross</a> was connected not only to the letter <a href="/wiki/Chi_(letter)" title="Chi (letter)">chi</a> but also to tau, the equivalent of the last letter in the <a href="/wiki/Phoenician_alphabet" title="Phoenician alphabet">Phoenician</a> and Old Hebrew alphabets, and which was originally cruciform in shape; see <a href="/wiki/Cross_of_Tau" class="mw-redirect" title="Cross of Tau">Cross of Tau</a>.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (January 2024)">citation needed</span></a></i>]</sup></li> <li>An essay written around 160 AD, attributed to <a href="/wiki/Lucian" title="Lucian">Lucian</a>, a mock legal prosecution called <i><a href="/wiki/The_Consonants_at_Law_-_Sigma_vs._Tau,_in_the_Court_of_the_Seven_Vowels" title="The Consonants at Law - Sigma vs. Tau, in the Court of the Seven Vowels">The Consonants at Law - Sigma vs. Tau, in the Court of the Seven Vowels</a></i>, contains a reference to the cross attribution. <a href="/wiki/Sigma_(letter)" class="mw-redirect" title="Sigma (letter)">Sigma</a> petitions the court to sentence Tau to death by crucifixion, saying: <dl><dd><i>Men weep, and bewail their lot, and curse Cadmus with many curses for introducing </i>Tau<i> into the family of letters; they say it was his body that tyrants took for a model, his shape that they imitated, when they set up structures on which men are crucified. </i>Stauros<i> (cross) the vile engine is called, and it derives its vile name from him. Now, with all these crimes upon him, does he not deserve death, nay, many deaths? For my part I know none bad enough but that supplied by his own shape — that shape which he gave to the <a href="/wiki/Gibbet" class="mw-redirect" title="Gibbet">gibbet</a> named </i>stauros<i> after him by men</i></dd></dl></li> <li><a href="/wiki/Tau_Cross" class="mw-redirect" title="Tau Cross">Tau</a> is usually considered as the symbol of <a href="/wiki/Franciscan" class="mw-redirect" title="Franciscan">Franciscan</a> orders due to <a href="/wiki/Saint_Francis_of_Assisi" class="mw-redirect" title="Saint Francis of Assisi">St. Francis'</a> love for it, symbol of the redemption and of the <a href="/wiki/Cross" title="Cross">Cross</a>. Almost all Franciscan churches have painted a tau with two crossing arms, both with <a href="/wiki/Stigmata" title="Stigmata">stigmata</a>, the one of Jesus and the other of Francis; members of the <a href="/wiki/Secular_Franciscan_Order" title="Secular Franciscan Order">Secular Franciscan Order</a> usually wear a wooden τ in a string with three knots around the neck</li> <li>The title and symbol of "Tau" is used by <a href="/wiki/Neo-Gnostic" class="mw-redirect" title="Neo-Gnostic">neo-Gnostic</a> bishops as it has some symbolism in many of the modern branches of Gnosticism.</li></ul> <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=Tau&action=edit&section=6" title="Edit section: Unicode"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>For the Greek and Coptic letter tau:<sup id="cite_ref-26" class="reference"><a href="#cite_note-26"><span class="cite-bracket">[</span>24<span class="cite-bracket">]</span></a></sup> </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+03A4</span> </span><span style="font-size:125%;line-height:1em">Τ</span> <span style="font-variant: small-caps; text-transform: lowercase; font-feature-settings: 'onum'">GREEK CAPITAL LETTER TAU</span> (<link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734" /><span class="monospaced">&Tau;</span>)</li> <li><span class="nowrap"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734" /><span class="monospaced">U+03C4</span> </span><span style="font-size:125%;line-height:1em">τ</span> <span style="font-variant: small-caps; text-transform: lowercase; font-feature-settings: 'onum'">GREEK SMALL LETTER TAU</span> (<link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734" /><span class="monospaced">&tau;</span>)</li> <li><span class="nowrap"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734" /><span class="monospaced">U+2CA6</span> </span><span style="font-size:125%;line-height:1em">Ⲧ</span> <span style="font-variant: small-caps; text-transform: lowercase; font-feature-settings: 'onum'">COPTIC CAPITAL LETTER TAU</span></li> <li><span class="nowrap"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734" /><span class="monospaced">U+2CA7</span> </span><span style="font-size:125%;line-height:1em">ⲧ</span> <span style="font-variant: small-caps; text-transform: lowercase; font-feature-settings: 'onum'">COPTIC SMALL LETTER TAU</span></li> <li><span class="nowrap"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734" /><span class="monospaced">U+1D6BB</span> </span><span style="font-size:125%;line-height:1em">𝚻</span> <span style="font-variant: small-caps; text-transform: lowercase; font-feature-settings: 'onum'">MATHEMATICAL BOLD CAPITAL TAU</span><sup id="cite_ref-27" class="reference"><a href="#cite_note-27"><span class="cite-bracket">[</span>a<span class="cite-bracket">]</span></a></sup></li> <li><span class="nowrap"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734" /><span class="monospaced">U+1D6D5</span> </span><span style="font-size:125%;line-height:1em">𝛕</span> <span style="font-variant: small-caps; text-transform: lowercase; font-feature-settings: 'onum'">MATHEMATICAL BOLD SMALL TAU</span></li> <li><span class="nowrap"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734" /><span class="monospaced">U+1D6F5</span> </span><span style="font-size:125%;line-height:1em">𝛵</span> <span style="font-variant: small-caps; text-transform: lowercase; font-feature-settings: 'onum'">MATHEMATICAL ITALIC CAPITAL TAU</span></li> <li><span class="nowrap"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734" /><span class="monospaced">U+1D70F</span> </span><span style="font-size:125%;line-height:1em">𝜏</span> <span style="font-variant: small-caps; text-transform: lowercase; font-feature-settings: 'onum'">MATHEMATICAL ITALIC SMALL TAU</span></li> <li><span class="nowrap"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734" /><span class="monospaced">U+1D72F</span> </span><span style="font-size:125%;line-height:1em">𝜯</span> <span style="font-variant: small-caps; text-transform: lowercase; font-feature-settings: 'onum'">MATHEMATICAL BOLD ITALIC CAPITAL TAU</span></li> <li><span class="nowrap"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734" /><span class="monospaced">U+1D749</span> </span><span style="font-size:125%;line-height:1em">𝝉</span> <span style="font-variant: small-caps; text-transform: lowercase; font-feature-settings: 'onum'">MATHEMATICAL BOLD ITALIC SMALL TAU</span></li> <li><span class="nowrap"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734" /><span class="monospaced">U+1D769</span> </span><span style="font-size:125%;line-height:1em">𝝩</span> <span style="font-variant: small-caps; text-transform: lowercase; font-feature-settings: 'onum'">MATHEMATICAL SANS-SERIF BOLD CAPITAL TAU</span></li> <li><span class="nowrap"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734" /><span class="monospaced">U+1D783</span> </span><span style="font-size:125%;line-height:1em">𝞃</span> <span style="font-variant: small-caps; text-transform: lowercase; font-feature-settings: 'onum'">MATHEMATICAL SANS-SERIF BOLD SMALL TAU</span></li> <li><span class="nowrap"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734" /><span class="monospaced">U+1D7A3</span> </span><span style="font-size:125%;line-height:1em">𝞣</span> <span style="font-variant: small-caps; text-transform: lowercase; font-feature-settings: 'onum'">MATHEMATICAL SANS-SERIF BOLD ITALIC CAPITAL TAU</span></li> <li><span class="nowrap"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734" /><span class="monospaced">U+1D7BD</span> </span><span style="font-size:125%;line-height:1em">𝞽</span> <span style="font-variant: small-caps; text-transform: lowercase; font-feature-settings: 'onum'">MATHEMATICAL SANS-SERIF BOLD ITALIC SMALL TAU</span></li></ul> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}</style><div class="reflist reflist-lower-alpha"> <div class="mw-references-wrap"><ol class="references"> <li id="cite_note-27"><span class="mw-cite-backlink"><b><a href="#cite_ref-27">^</a></b></span> <span class="reference-text">The <span class="smallcaps"><span style="font-variant: small-caps; text-transform: lowercase;">MATHEMATICAL</span></span> characters are used only in math. Stylized Greek text should be encoded using the normal Greek letters, with markup and formatting to indicate text style.</span> </li> </ol></div></div> <div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Tau&action=edit&section=7" title="Edit section: See also"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/Greek_letters_used_in_mathematics,_science,_and_engineering" title="Greek letters used in mathematics, science, and engineering">Greek letters used in mathematics, science, and engineering</a></li></ul> <div class="mw-heading mw-heading2"><h2 id="Notes">Notes</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Tau&action=edit&section=8" title="Edit section: Notes"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239543626" /><div class="reflist"> <div class="mw-references-wrap"><ol class="references"> <li id="cite_note-:0-11"><span class="mw-cite-backlink">^ <a href="#cite_ref-:0_11-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-:0_11-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-:0_11-2"><sup><i><b>c</b></i></sup></a></span> <span class="reference-text">The date given on the source is after that of the archive. This is because the original publishing date is unknown, so the latest update date is stated instead.</span> </li> <li id="cite_note-:1-17"><span class="mw-cite-backlink"><b><a href="#cite_ref-:1_17-0">^</a></b></span> <span class="reference-text">The archived version of this source may take a few minutes to render the <a href="/wiki/TeX" title="TeX">TeX</a> math codes properly.</span> </li> </ol></div></div> <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=Tau&action=edit&section=9" title="Edit section: References"><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"><a href="/wiki/File:Wiktionary-logo-en-v2.svg" class="mw-file-description"><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" /></a></span></div> <div class="side-box-text plainlist">Look up <i><b><a href="https://en.wiktionary.org/wiki/%CE%A4" class="extiw" title="wiktionary:Τ">Τ</a></b></i> or <i><b><a href="https://en.wiktionary.org/wiki/%CF%84" class="extiw" title="wiktionary:τ">τ</a></b></i> in Wiktionary, the free dictionary.</div></div> </div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239543626" /><div class="reflist"> <div class="mw-references-wrap mw-references-columns"><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-tau" 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=tau">"tau"</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=tau&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%3Dtau&rfr_id=info%3Asid%2Fen.wikipedia.org%3ATau" 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><br /><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite class="citation encyclopaedia cs1"><a rel="nofollow" class="external text" href="https://www.dictionary.com/browse/tau">"tau"</a>. <i><a href="/wiki/Dictionary.com" title="Dictionary.com">Dictionary.com Unabridged</a></i> (Online). n.d.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=bookitem&rft.atitle=tau&rft.btitle=Dictionary.com+Unabridged&rft_id=https%3A%2F%2Fwww.dictionary.com%2Fbrowse%2Ftau&rfr_id=info%3Asid%2Fen.wikipedia.org%3ATau" class="Z3988"></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"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20120720081320/http://oxforddictionaries.com/definition/english/tau">"Oxford Dictionaries Online"</a>. 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Retrieved <span class="nowrap">2025-01-31</span></span>. <q>The Thue-Morse sequence, also called the Morse-Thue sequence or Prouhet-Thue-Morse sequence (Allouche and Cosnard 2000), is one of a number of related sequences of numbers obtained from the parities of the counts of 1's in the binary representation of the nonnegative integers.</q></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=mathworld.wolfram.com&rft.atitle=Thue-Morse+Sequence&rft.aulast=Weisstein&rft.aufirst=Eric+W.&rft_id=https%3A%2F%2Fmathworld.wolfram.com%2FThue-MorseSequence.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ATau" class="Z3988"></span></span> </li> <li id="cite_note-22"><span class="mw-cite-backlink"><b><a href="#cite_ref-22">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFElert2023" class="citation cs2">Elert, Glenn (2023), <a rel="nofollow" class="external text" href="https://physics.info/symbols/">"Special Symbols"</a>, <i>The Physics Hypertextbook</i>, hypertextbook<span class="reference-accessdate">, retrieved <span class="nowrap">2025-02-01</span></span>, <q>τ shear stress</q></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=The+Physics+Hypertextbook&rft.atitle=Special+Symbols&rft.date=2023&rft.aulast=Elert&rft.aufirst=Glenn&rft_id=https%3A%2F%2Fphysics.info%2Fsymbols%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3ATau" class="Z3988"></span></span> </li> <li id="cite_note-23"><span class="mw-cite-backlink"><b><a href="#cite_ref-23">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFElert2023" class="citation cs2">Elert, Glenn (2023), <a rel="nofollow" class="external text" href="https://physics.info/symbols/">"Special Symbols"</a>, <i>The Physics Hypertextbook</i>, hypertextbook<span class="reference-accessdate">, retrieved <span class="nowrap">2025-02-01</span></span>, <q>τ time constant</q></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=The+Physics+Hypertextbook&rft.atitle=Special+Symbols&rft.date=2023&rft.aulast=Elert&rft.aufirst=Glenn&rft_id=https%3A%2F%2Fphysics.info%2Fsymbols%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3ATau" class="Z3988"></span></span> </li> <li id="cite_note-24"><span class="mw-cite-backlink"><b><a href="#cite_ref-24">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFWeisstein" class="citation web cs1">Weisstein, Eric W. <a rel="nofollow" class="external text" href="https://mathworld.wolfram.com/Tau.html">"Tau"</a>. <i>mathworld.wolfram.com</i><span class="reference-accessdate">. Retrieved <span class="nowrap">2025-02-01</span></span>. <q>The symbol also has a number of other different meanings in physics, for example the tau particle, tau neutrino, as a symbol for torque, etc.</q></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=mathworld.wolfram.com&rft.atitle=Tau&rft.aulast=Weisstein&rft.aufirst=Eric+W.&rft_id=https%3A%2F%2Fmathworld.wolfram.com%2FTau.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ATau" class="Z3988"></span></span> </li> <li id="cite_note-25"><span class="mw-cite-backlink"><b><a href="#cite_ref-25">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFElert2023" class="citation cs2">Elert, Glenn (2023), <a rel="nofollow" class="external text" href="https://physics.info/symbols/">"Special Symbols"</a>, <i>The Physics Hypertextbook</i>, hypertextbook<span class="reference-accessdate">, retrieved <span class="nowrap">2025-02-01</span></span>, <q><b>τ</b>, τ torque</q></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=The+Physics+Hypertextbook&rft.atitle=Special+Symbols&rft.date=2023&rft.aulast=Elert&rft.aufirst=Glenn&rft_id=https%3A%2F%2Fphysics.info%2Fsymbols%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3ATau" class="Z3988"></span></span> </li> <li id="cite_note-26"><span class="mw-cite-backlink"><b><a href="#cite_ref-26">^</a></b></span> <span class="reference-text">Unicode: "<a rel="nofollow" class="external text" href="https://www.unicode.org/charts/PDF/U0370.pdf">Greek and Coptic (Range: 0370-03FF)</a>".</span> </li> </ol></div></div> <div class="navbox-styles"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374" /><style data-mw-deduplicate="TemplateStyles:r1236075235">.mw-parser-output .navbox{box-sizing:border-box;border:1px solid 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