Template:Short description Template:More citations needed "Õ" (uppercase), or "õ" (lowercase) is a composition of the Latin letter O with the diacritic mark tilde. Template:Infobox grapheme The HTML entity is Õ for Õ and õ for õ.
RomagnolEdit
For Romagnol language, õ is used in some proposed orthographies to represent {{#invoke:IPA|main}}, e.g. savõ {{#invoke:IPA|main}} "soap". To this day a unified standardization has not been established.
EstonianEdit
In Estonian, Õ is the 27th letter of the alphabet (between W and Ä), and it represents a vowel characteristic of Estonian, the unrounded back vowel {{#invoke:IPA|main}}, which may be close-mid back, close back, or close-mid central.<ref name="Asu 2009 369">Template:Harvcoltxt</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 to approximate this letter.
In most parts of the island Saaremaa, Õ is pronounced the same as Ö.
GuaraniEdit
In the Guarani language, Õ is the 22nd letter and fourth nasal vowel of the alphabet, similar to the Spanish "o", but with a stressed nasalization.
HungarianEdit
In Hungarian, Õ only appears when a typeface (font set) does not contain a proper "ő" letter, which is an "o" with a double acute diacritic.
SamogitianEdit
In Samogitian the letter Õ represents, as in Estonian, the unrounded back vowel {{#invoke:IPA|main}} 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.
PortugueseEdit
In the Portuguese language, the symbol Õ stands for a nasal close-mid back rounded vowel, also written {{#invoke:IPA|main}} in IPA. It is not considered an independent letter of the alphabet: the tilde is the standard diacritic for nasalization.
VietnameseEdit
In the Vietnamese language, the symbol Õ stands for the sound {{#invoke:IPA|main}} 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/ỡ.
VõroEdit
In the Võro language, this letter is the 25th letter of the alphabet, pronounced as in Estonian.<ref>Omniglot</ref>
Skolt SamiEdit
In the Skolt Sami language, this letter is the 25th letter of the alphabet, pronounced as [[[:Template:IPAlink]]].
VokoEdit
In the Voko language, the letter Õ represents 'ɔ̀ŋ'.
Mathematical useEdit
The symbol, pronounced soft-O, is used as a variant of big O notation to measure growth rate that ignores logarithmic factors.<ref name=":0">Template:Cite book</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 encodingEdit
Due to character encoding confusion, the letters can be seen on many incorrectly coded Hungarian web pages, representing 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 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.