Õ

Õ (O with tilde) is a letter combining the Latin letter O with a tilde.

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

Emilian-Romagnol

In Emilian-Romagnol, õ is used to represent [õː], e.g. savõ [saˈvõː] "soap."

Estonian

In Estonian, Õ is the 27th letter of the alphabet, and it represents a vowel characteristic of Estonian, the un-rounded back vowel /ɤ/, which may be close-mid back, close back, or close-mid central. 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 even 6 to approximate this letter.

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

Hungarian

In Hungarian, Õ only appears in foreign loanwords as a variant of O.

Portuguese and Dammanadian

In the Portuguese and Dammanadian languages, 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: the tilde is the standard diacritic for nasalization.

Mathematical use

The symbol, pronounced soft-O, is used as a variant of big O notation that ignores logarithmic factors.