View source for Iota

{{Short description|Ninth letter in the Greek alphabet}}
{{Hatnote group|
{{About-distinguish|Greek iota|Jota (disambiguation){{!}}Jota}}{{For-multi|Latin iota|ɩ|Cyrillic Iota|Iota (Cyrillic)|other uses}}
{{Distinguish|Yota}}
}}
{{Refimprove|date=December 2009}}
{{Greek Alphabet|letter=iota<!--|image=Greek alphabet iota.svg-->}} <!-- Image Wasn't working -->

'''Iota''' ({{IPAc-en|aɪ|ˈ|oʊ|t|ə|audio=LL-Q1860 (eng)-Flame, not lame-Iota.wav}};<ref>{{OED|iota}}</ref> {{IPA|/ˈjota/}}, uppercase '''Ι''', lowercase '''ι'''; {{Langx|el|ιώτα}}) is the ninth letter of the [[Greek alphabet]]. It was derived from the [[Phoenician alphabet|Phoenician]] letter [[Yodh]].<ref>Victor Parker, ''A History of Greece, 1300 to 30 BC'', (John Wiley & Sons, 2014), 67.</ref> Letters that arose from this letter include the [[Latin alphabet|Latin]] [[I]] and [[J]], the [[Cyrillic]] [[І]] (І, і), [[Yi (Cyrillic)|Yi]] (Ї, ї), and [[Je (Cyrillic)|Je]] (Ј, ј), and [[Iotation|iotated]] letters (e.g. [[Yu (Cyrillic)|Yu]] (Ю, ю)). In the system of [[Greek numerals]], iota has a value of 10.<ref>{{cite web|url=http://www-history.mcs.st-and.ac.uk/HistTopics/Greek_numbers.html |title=Greek numbers |publisher=History.mcs.st-and.ac.uk |access-date=2014-05-04}}</ref>

Iota represents the [[close front unrounded vowel]] {{IPA|el|i|IPA}}. In early forms of ancient Greek, it occurred in both long {{IPA|[iː]}} and short {{IPA|[i]}} versions, but this distinction was lost in [[Koine Greek phonology|Koine Greek]].<ref name="kgp" /> Iota participated as the second element in [[falling diphthong]]s, with both long and short vowels as the first element. Where the first element was long, the iota was lost in pronunciation at an early date, and was written in [[polytonic orthography]] as [[iota subscript]], in other words as a very small ι under the main vowel. Examples include ᾼ ᾳ ῌ ῃ ῼ ῳ. The former diphthongs became [[digraph (orthography)|digraph]]s for simple vowels in [[Koine Greek]].<ref name="kgp">see [[Koine Greek phonology]]</ref>

The word is used in a common English phrase, "not one iota", meaning "not the slightest amount". This refers to iota, the smallest letter, or possibly [[yodh]], י, the smallest letter in the Hebrew alphabet.<ref>{{Cite web |date=2020-03-30 |title=Yud (Hebrew Letter) - BJE |url=https://bje.org.au/knowledge-centre/jewish-languages/hebrew-alphabet/yud/ |access-date=2025-03-21 |language=en-US}}</ref><ref>{{Cite web |last=Tverberg |first=Lois |date=2015-06-30 |title=Yod - One Very Significant Letter |url=https://engediresourcecenter.com/2015/06/30/yod-one-very-significant-letter/#gsc.tab=0 |access-date=2025-03-21 |website=En-Gedi Resource Center |language=en-US}}</ref> The English word ''[[wikt:jot#English|jot]]'' derives from iota.<ref>{{cite web|url=http://dictionary.reference.com/browse/jot |title=Jot &#124; Define Jot at Dictionary.com |publisher=Dictionary.reference.com |access-date=2014-05-04}}</ref> The German, Polish, Portuguese, and Spanish name for the letter J (''[[wikt:Jot#German|Jot]]'' / ''[[wikt:jota#Spanish|jota]]'') is derived from iota.

==<span class="anchor" id="Symbol"></span> Uses==

* In some [[programming language]]s (e.g., [[A+ (programming language)|A+]], [[APL (programming language)|APL]], [[C++]],<ref>{{Cite web|url=https://sean-parent.stlab.cc/2019/01/04/iota.html|title=#iotashaming|last=Parent|first=Sean|date=2019-01-04|website=sean-parent.stlab.cc|access-date=2020-03-11}}</ref> [[Go (programming language)|Go]]<ref>{{cite web|url=https://golang.org/ref/spec#Iota |title=The Go Programming Language Specification |publisher=The Go Authors |date=November 18, 2016 |access-date=2017-08-08}}</ref>), iota (either as the lowercase symbol <code>⍳</code> or the identifier <code>iota</code>) is used to represent and generate an array of consecutive integers. For example, in APL <code>⍳4</code> gives <code>1 2 3 4</code>.<ref>{{Cite book |title=Functional programming and its applications: an advanced course |date=1991 |publisher=University Microfilms International |isbn=978-0-521-24503-6 |editor-last=Darlington |editor-first=John |edition=Xerographic reprint [d. Ausg.] Cambridge 1982 |location=Ann Arbor, Mich |pages=76 |quote=iota The APL ι operator: iota apply to an integer ''n'' produces a sequence of ''n'' consecutive integers starting from 1;}}</ref>
* The lowercase iota symbol is sometimes used to write the [[imaginary unit]], but more often Roman [[i]] or [[j]] is used.
* In [[mathematics]], the [[inclusion map]] of one space into another is sometimes denoted by the lowercase iota.
* In [[logic]], the lowercase iota denotes the [[Definite description#Symbolic form|definite descriptor]].

==Unicode==
For accented Greek characters, see [[Greek diacritics#Computer encoding|Greek diacritics: Computer encoding]].

* {{unichar|0196|html=}}
* {{unichar|0269|html=}}
* {{unichar|0345|html=}}
* {{unichar|037A|nlink=}}
* {{unichar|038A|html=}}
* {{unichar|0390|html=}}
* {{unichar|0399|html=}}
* {{unichar|03AA|html=}}
* {{unichar|03AF|html=}}
* {{unichar|03B9|html=}} ({{tt|\iota}} in TeX)
* {{unichar|03CA|html=}}
* {{unichar|1D7C|html=}}
* {{unichar|1DA5|html=}}
* {{unichar|1FBE|html=}}
* {{unichar|2129|html=}}
* {{unichar|2373|html=}}
* {{unichar|2378|html=}}
* {{unichar|2C92|html=}}
* {{unichar|2C93|html=}}
* {{unichar|A646|html=}}
* {{unichar|A647|html=}}
* {{unichar|1D6B0|html=}}{{efn|The {{sc|mathematical}} symbols are only for use in math. Stylized Greek text should be encoded using the normal Greek letters, with markup and formatting to indicate text style.}}
* {{unichar|1D6CA|html=}}
* {{unichar|1D6EA|html=}}
* {{unichar|1D704|html=}}
* {{unichar|1D724|html=}}
* {{unichar|1D73E|html=}}
* {{unichar|1D75E|html=}}
* {{unichar|1D778|html=}}
* {{unichar|1D798|html=}}
* {{unichar|1D7B2|html=}}
{{notelist}}

==See also==
*[[Hurricane Iota]]

==References==
{{Commons category|Iota (letter)}}
{{Wiktionary|Ι|ι}}
{{Reflist}}

[[Category:Greek letters]]
[[Category:Vowel letters]]