Double acute accent

The double acute accent (◌̋) is a diacritic mark of the Latin and Cyrillic scripts. It is used primarily in Hungarian or Chuvash, and consequently it is sometimes referred to by typographers as hungarumlaut. The signs formed with a regular umlaut are letters in their own right in the Hungarian alphabet—for instance, they are separate letters for the purpose of collation. Letters with the double acute, however, are considered variants of their equivalents with the umlaut, being thought of as having both an umlaut and an acute accent.

Length marks first appeared in Hungarian orthography in the 15th-century Hussite Bible. Initially, only á and é were marked, since they are different in quality as well as length. Later í, ó, ú were marked as well.

In the 18th century, before Hungarian orthography became fixed, u and o with umlaut + acute (ǘ, ö́) were used in some printed documents. 19th century typographers introduced the double acute as a more aesthetic solution.

In Hungarian, the double acute is thought of as the letter having both an umlaut and an acute accent. Standard Hungarian has 14 vowels in a symmetrical system: seven short vowels (a, e, i, o, ö, u, ü) and seven long ones, which are written with an acute accent in the case of á, é, í, ó, ú, and with the double acute in the case of ő, ű. Vowel length has phonemic significance in Hungarian, that is, it distinguishes different words and grammatical forms.

At the beginning of the 20th century, the letter A̋ (A with double acute) was used in Slovak as a long variant of the short vowel Ä (A with diaeresis), representing the vowel /æː/ in dialect and some loanwords. The letter is still used for this purpose in Slovak phonetic transcription systems.

In handwriting in German and Swedish, the umlaut is sometimes written similarly to a double acute. In the Swedish alphabet, Å, Ä and Ö are letters in their own right.

The Chuvash language written in the Cyrillic script uses a double-acute Ӳ, ӳ /y/ as a front counterpart of Cyrillic letter У, у /u/ (see Chuvash vowel harmony), likely after the analogy of handwriting in Latin script languages. In other minority languages of Russia (Khakas, Mari, Altai, and Khanty), the umlauted form Ӱ is used instead.

Classical Danish handwriting uses "ó" for "ø", which becomes a problem when writing Faroese in the same tradition, as "ó" is a part of the Faroese alphabet. Thus ő is sometimes used for ø in Faroese.