Õ

Not to be confused with Ő, O with double acute.

Õ

õ

"Õ", or "õ" is a composition of the Latin letter O with the diacritic mark tilde.

The HTML entity is Õ for Õ and õ for õ.

Estonian

In Estonian, Õ is the 24th letter of the alphabet (between V and Ä), representing the close-mid back unrounded vowel sound [ɤ]. The vowel had previously been marked with Ö, but in early 19th century, Otto Wilhelm Masing adopted the letter Õ, ending the confusion between several homographs and showing clearly 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.

Portuguese

In the Portuguese language, the symbol Õ stands for a nasal close-mid back rounded vowel, also written [õ] in IPA. It is not considered an independent letter of the alphabet.

Vietnamese

In the Vietnamese language, the symbol Õ stands for the sound [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/ỡ.

Võro

In the Võro language, this letter is the 25th letter of the alphabet, pronounced as in Estonian.^[1]

Mathematical use

The symbol, pronounced soft-O, is used as a variant of big O notation that ignores logarithmic factors. Thus, f(n) = Õ(g(n)) is shorthand for f(n) = O(g(n)log ^kg(n)) for some k.

Encoding problems

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.

References

1. ^ Omniglot

See also

• Ã
• Tilde

The ISO basic Latin alphabetv · d · e
Aa	Bb	Cc	Dd	Ee	Ff	Gg	Hh	Ii	Jj	Kk	Ll	Mm	Nn	Oo	Pp	Qq	Rr	Ss	Tt	Uu	Vv	Ww	Xx	Yy	Zz
Letter O with diacritics
Óó	Òò	Ŏŏ	Ôô	Ốố	Ồồ	Ỗỗ	Ổổ	Ǒǒ	Öö	Ȫȫ	Őő	Õõ	Ṍṍ	Ṏṏ	Ȭȭ	Ȯȯ	O͘o͘	Ȱȱ	Øø	Ǿǿ	Ǫǫ	Ǭǭ	Ōō	Ṓṓ	Ṑṑ
Ỏỏ	Ȍȍ	Ȏȏ	Ơơ	Ớớ	Ờờ	Ỡỡ	Ởở	Ợợ	Ọọ	Ộộ	Ɵɵ	Ɔɔ	ⱺ
Letters using tilde sign ( ◌̃ )
Ãã	Ẽẽ	Ĩ ĩ	Ññ	Õõ	P̃p̃	Ũũ	Ṽṽ	Ỹỹ
Related
History Palaeography Derivations Diacritics Punctuation Numerals Unicode List of letters ISO/IEC 646