The umlaut (ˈʊmlaʊt) is the diacritical mark used to indicate in writing (as part of the letters , , and ) the result of the historical sound shift due to which former back vowels are now pronounced as front vowels (for example a, ɔ, and ʊ as ɛ, œ, and ʏ). (The term [Germanic] umlaut is also used for the underlying historical sound shift process.)
In its contemporary printed form, the mark consists of two dots placed over the letter to represent the changed vowel sound. It looks identical to the diaeresis mark used in other European languages and is represented by the same Unicode code point. The word trema (tréma), used in linguistics and also classical scholarship, describes the form of both the umlaut diacritic and the diaeresis rather than their function and can therefore be used to refer to both.
Umlaut (literally "changed sound") is the German name of the sound shift phenomenon also known as i-mutation. In German, this term is also used for the corresponding letters ä, ö, and ü (and the diphthong äu) and the sounds that these letters represent. In German, the combination of a letter with the diacritical mark is called Umlaut, while the marks themselves are called Umlautzeichen (literally "umlaut sign").
In German, the umlaut diacritic indicates that the short back vowels and the diphthong aʊ are pronounced ("shifted forward in the mouth") as follows:
a → ɛ
ɔ → œ
ʊ → ʏ
aʊ → ɔʏ
And the long back vowels are pronounced in the front of the mouth as follows:
aː → very formal/old fashioned ɛː, in most speakers eː (resulting in a merger with /eː/)
oː → øː
uː → yː
In modern German orthography, the affected graphemes , , , and are written as , , , and , i.e. they are written with the umlaut diacritic, which looks identical to the diaeresis mark used in other European languages and is represented by the same Unicode character.
The Germanic umlaut is a specific historical phenomenon of vowel-fronting in German and other Germanic languages, including English. English examples are 'man ~ men' and 'foot ~ feet' (from Proto-Germanic *fōts, pl.