Ö

Ö, or ö, is a character that represents either a letter from several extended Latin alphabets, or the letter "o" modified with an umlaut or diaeresis. Ö, or ö, is a variant of the letter O. In many languages, the letter "ö", or the "o" modified with an umlaut, is used to denote the close- or open-mid front rounded vowels [ø] ^ⓘ or [œ] ^ⓘ; compare the vowel in "girl", which in these languages phonetically could be written: /görl/. In languages without such vowels, the character is known as an "o with diaeresis" and denotes a syllable break, wherein its pronunciation remains an unmodified [o].

The letter o with umlaut (ö) appears in the German alphabet. It represents the umlauted form of o, resulting in [œ] or [ø]. The letter is often collated together with o in the German alphabet, but there are exceptions which collate it like oe or OE. The letter also occurs in some languages that have adopted German names or spellings, but it is not normally a part of those alphabets. In Danish and Norwegian, ö was previously used in place of ø in older texts to distinguish between open and closed ö-sounds. It is also used when confusion with other symbols could occur, on maps for instance. The Danish/Norwegian ø is, like the German/Swedish ö, a development of oe and can be compared with the French œ. In other languages that do not have the letter as part of the regular alphabet or in limited character sets such as ASCII, o-umlaut is frequently replaced with the digraph oe. For example, German hören (hear/listen) can be easily recognized even if spelled hoeren.

The letter ö also occurs in two other Germanic languages: Swedish and Icelandic, but it is regarded there as a separate letter, not as an orthographic variation of the letter o. Apart from Germanic languages, it occurs in the Uralic languages such as Finnish, Karelian, Veps, Estonian, Southern Sami, and Hungarian, in the Turkic languages such as Azeri, Turkish, Turkmen, Uyghur (Latin script), Crimean Tatar, Kazakh, and in the Uto-Aztecan language Hopi, where it represents the vowel sounds [ø, œ]. Its name in Finnish, Swedish, Icelandic, Estonian, Azeri, Turkish, Turkmen, Uyghur, Crimean Tatar, Hungarian, Votic and Volapük is Öö [øː], not "O with two dots" since /ø/ is not a variant of the vowel /o/ but a distinct phoneme.

In mountain dialects of Emilian, it is used to represent [ø], e.g. tött [tøtː] "all".

In the Dutch language, ⟨ö⟩ appears only as O-diaeresis - see below. The sound /øː/ is spelled with the digraph ⟨eu⟩, as in deur /døːr/ 'door'. In the Dutch-based orthographies of Low Saxon, Limburgish and Ripuarian, ⟨ö⟩ is used only for the short /œ/ (as in Maastrichtian bös /bœs/ 'bus'), whereas the long /œː/ (lowered to /ɶː/ in Maastricht) and /øː/ are typically written unambiguously with ⟨äö⟩ (since it is often an umlauted form of ⟨ao⟩, /ɔː/ in IPA) and ⟨eu⟩, the latter following the Standard Dutch spelling. The example words (in Maastrichtian) are väöl /vɶːl/ 'a lot' and beuk /bøːk/ 'beech'. The short close-mid /ø/ (which instead can be transcribed in IPA with ⟨ʏ⟩) tends to be spelled with ⟨u⟩ (as in Maastrichtian stum /støm/ 'voice'), but this can also be used for /y(ː)/ in open syllables, again following the Standard Dutch spelling. On the German side of the border, ⟨ö⟩ can be used for any of the /œ, œː, ø, øː/ (thus Bös(s), vö(h)l, Stömm, Bö(h)k), whereas /y(ː)/ is always written distinctly, as ⟨ü(h)⟩. ⟨u⟩ is never used for any of the aforementioned front vowels; instead, it denotes the close back rounded vowel /u(ː)/, as in Standard German. The length is usually disambiguated by doubling the following consonant (which denotes the short /œ, ø/), not doubling it or adding a silent ⟨h⟩ after ⟨ö⟩ (both denoting the long /œː, øː/). The exact height normally remains ambiguous, but the open-mid /œ(ː)/ can be disambiguated by adding a grave accent above ⟨ö⟩, as in ⟨ö̀⟩ (thus bö̀ss, vö̀(h)l), similarly to some Swiss German orthographies. This is not the usual practice, not least because the diacritics end up stacked on top of one another.

In certain languages, the letter ö cannot be written as "oe" because minimal pairs exist between ö and oe (and also with oo, öö and öe), as in Finnish eläinkö "animal?" (interrogative) vs. eläinkoe "animal test" (cf. Germanic umlaut). If the character ö is unavailable, o is substituted and context is relied upon for inference of the intended meaning. In Volapük, ö can be written as oy, but never as oe. In the aforementioned Dutch-based orthographies of Low Saxon, Limburgish and Ripuarian, ⟨ö⟩ also cannot be written with ⟨oe⟩ because the latter denotes the close back /u(ː)/, as in Standard Dutch. Thus, Maastrichtian bös /bœs/ 'bus' cannot be spelled *boes because it is not pronounced */buːs/ (cf. moes /muːs˦/ 'mouse'). The German-based orthographies, in which /u(ː)/ is always spelled ⟨u(h)⟩, have no such limitation. In those, ⟨oe⟩ is read as identical with ⟨ö⟩, same as in Standard German.

In Romagnol, ö is used to represent [ɔə~ɔː], e.g. cöt [kɔət~kɔːt] "cooked".

In the Seneca language, ö is used to represent [ɔ̃], a back mid rounded nasalized vowel.