View source for Õ

{{short description|Latin letter O with tilde}}
{{More citations needed|date=July 2009}}
"'''Õ'''" (uppercase), or "'''õ'''" (lowercase) is a composition of the [[Latin alphabet|Latin letter]] [[O]] with the [[diacritic]] mark [[tilde]].
{{Infobox grapheme
|letter=Õ õ
|image=Latin letter O with tilde.svg
|imageclass=skin-invert-image
|name=O with tilde
|fam1=[[Oᷠ]] [[oᷠ]]
|phonemes={{grid list|[{{IPAlink|õː}}]|[{{IPAlink|o}}]|[{{IPAlink|ɤ}}]|[{{IPAlink|õ}}]|[{{IPAlink|ɔ̀ŋ}}]|[{{IPAlink|ɘ}}]}}
|variations=[[Ö|Ö ö]]
|children=[[Ỗ|Ỗ ỗ]], [[Ỡ|Ỡ ỡ]]
|unicode=U+00D5, U+00F5
|type=alphabet|typedesc=ic|script=[[Latin script]]}}
The [[HTML entity]] is ''&amp;Otilde;'' for Õ and ''&amp;otilde;'' for õ.

== Romagnol ==
For [[Romagnol|Romagnol language]], ''õ'' is used in some proposed orthographies to represent {{IPA|[õː]}}, e.g. ''savõ'' {{IPA|[saˈvõː]}} "soap". To this day a unified standardization has not been established.

==Estonian==
In [[Estonian language|Estonian]], ''Õ'' is the 27th letter of the [[Estonian alphabet|alphabet]] (between [[W]] and [[Ä]]), and it represents a vowel characteristic of Estonian, the unrounded back vowel {{IPA|/ɤ/}}, which may be [[close-mid back unrounded vowel|close-mid back]], [[close back unrounded vowel|close back]], or [[close-mid central unrounded vowel|close-mid central]].<ref name="Asu 2009 369">{{Harvcoltxt|Asu|Teras|2009|p=369}}</ref> The vowel was previously written with the letter [[Ö]], but in the early 19th century, [[Otto Wilhelm Masing]] adopted the letter ''Õ'', ending the confusion between several homographs and clearly showing how to pronounce a word.

In informal writing, e.g., emails, instant messaging and when using foreign keyboard layouts where the letter ''Õ'' is not available, some Estonians use the characters [[O]] or [[6 (number)|6]] to approximate this letter.

In most parts of the island [[Saaremaa]], ''Õ'' is pronounced the same as ''Ö''.

==Guarani==

In the [[Guarani language]], ''Õ'' is the 22nd letter and fourth nasal vowel of the alphabet, similar to the [[Spanish language|Spanish]] "o", but with a [[Nasalization|stressed nasalization]].

== Hungarian ==
In [[Hungarian language|Hungarian]], Õ only appears when a typeface (font set) does not contain a proper "'''ő'''" letter, which is an "'''o'''" with a [[Double acute accent|double acute diacritic]].

==Samogitian==
In [[Samogitian dialect|Samogitian]] the letter ''Õ'' represents, as in Estonian, the unrounded back vowel {{IPA|/ɤ/}} which is unique to Samogitian and is not found in Standard Lithuanian, this is a rather new innovation brought on by the ensuing efforts of standardising Samogitian, this letter alleviates the confusion between the two distinct pronunciations of the letter '''ė'''.

==Portuguese==
In the [[Portuguese language]], the symbol ''Õ'' stands for a [[nasal vowel|nasal]] [[close-mid back rounded vowel]], also written {{IPA|[õ]}} in IPA. It is not considered an independent letter of the [[portuguese alphabet|alphabet]]: the tilde is the standard diacritic for [[nasalization]].

==Vietnamese==
In the [[Vietnamese language]], the symbol ''Õ'' stands for the sound {{IPA|[ɔ]}} with [[creaky voice]] (rising tone with a glottal break followed by a continuation of the rising tone). Vietnamese also has derived letters '''[[Ỗ]]'''/'''ỗ''' and '''[[Ỡ]]'''/'''[[Ơ|ỡ]]'''.

==Võro==
In the [[Võro language]], this letter is the 25th letter of the alphabet, pronounced as in Estonian.<ref>[http://www.omniglot.com/writing/voro.htm Omniglot]</ref>

==Skolt Sami==
In the [[Skolt Sami language]], this letter is the 25th letter of the alphabet, pronounced as [{{IPAlink|ɘ}}].

==Voko==
In the [[Voko language]], the letter ''Õ'' represents 'ɔ̀ŋ'.

==Mathematical use==
The symbol, pronounced [[Big oh notation#Extensions to the Bachmann–Landau notations|soft-''O'']], is used as a variant of [[big O notation|big ''O'' notation]] to measure [[Asymptotic analysis|growth rate]] that ignores [[Polylogarithmic function|logarithmic factors]].<ref name=":0">{{Cite book|title=Introduction to algorithms|url=https://archive.org/details/introductiontoal00corm_805|url-access=limited|date=2009|publisher=MIT Press|others=Cormen, Thomas H.|isbn=978-0-262-27083-0|edition=Third|location=Cambridge, Mass.|oclc=676697295|page=[https://archive.org/details/introductiontoal00corm_805/page/n83 63]}}</ref> Thus, <math>f(n)\in\tilde{O}(g(n))</math> is [[shorthand]] for <math>\exists k:f(n) \in O(g(n) \log^kn)</math>.<ref name=":0" />

==Computer encoding==
Due to [[character encoding]] confusion, the letters can be seen on many incorrectly coded [[Hungarian language|Hungarian]] web pages, representing [[Ő|'''Ő'''/'''ő''']] (letter O with [[double acute accent]]). This can happen due to said characters sharing a [[code point]] in the [[ISO 8859-1]] and [[ISO 8859-2|8859-2]] character sets, as well as the [[Windows-1252]] and [[Windows-1250]] character sets, and the web site designer forgetting to set the correct [[code page]]. '''Õ''' is not part of the Hungarian alphabet. The usage of [[Unicode]] avoids this type of problems. In [[LaTeX]] the option of using "\~o" and "\~O" exists.

{{charmap
| 00D5 | name1 = Latin Capital Letter O with Tilde
| 00F5 | name2 = Latin Small Letter O with Tilde
| map1 = [[EBCDIC]] family | map1char1 = EF | map1char2 = CF
| map2 = [[ISO 8859]]-[[ISO 8859-1|1]]/[[ISO 8859-4|4]]/[[ISO 8859-9|9]]/[[ISO 8859-10|10]]/[[ISO 8859-13|13]]/[[ISO 8859-14|14]]/[[ISO 8859-15|15]]/[[ISO 8859-16|16]] | map2char1 = D5 | map2char2 = F5
}}

==See also==
*[[Ã]]
*[[Tilde]]

==References==
{{Reflist}}

{{refbegin}}
* {{citation
|last=Asu
|first=Eva Liina
|last2=Teras
|first2=Pire
|year=2009
|title=Estonian
|journal=Journal of the International Phonetic Association
|volume=39
|issue=3
|pages=367–372
|doi=10.1017/s002510030999017x
|doi-access=free
}}
{{refend}}

{{Latin script}}

{{DEFAULTSORT:O-Tilde}}
[[Category:Latin letters with diacritics]]
[[Category:Vowel letters]]