In phonology, hiatus, diaeresis (), or dieresis describes the occurrence of two separate vowel sounds in adjacent

syllable A syllable is a unit of organization for a sequence of speech sounds typically made up of a syllable nucleus (most often a vowel) with optional initial and final margins (typically, consonants). Syllables are often considered the phonological "bu ...

s with no intervening consonant. When two vowel sounds instead occur together as part of a single syllable, the result is called a

diphthong A diphthong ( ; , ), also known as a gliding vowel, is a combination of two adjacent vowel sounds within the same syllable. Technically, a diphthong is a vowel with two different targets: that is, the tongue (and/or other parts of the speech o ...

Preference

Some languages do not have diphthongs, except sometimes in rapid speech, or they have a limited number of diphthongs but also numerous vowel sequences that cannot form diphthongs and so appear in hiatus. That is the case of Japanese, Nuosu,

Bantu languages The Bantu languages (English: , Proto-Bantu: *bantʊ̀) are a large family of languages spoken by the Bantu people of Central, Southern, Eastern africa and Southeast Africa. They form the largest branch of the Southern Bantoid languages. The t ...

Swahili Swahili may refer to: * Swahili language, a Bantu language official in Kenya, Tanzania and Uganda and widely spoken in the African Great Lakes * Swahili people, an ethnic group in East Africa * Swahili culture Swahili culture is the culture of ...

, and Lakota. Examples are Japanese () 'blue/green', and Swahili 'purify', both with three syllables.

Avoidance

Many languages disallow or restrict hiatus and avoid it by deleting or assimilating the vowel or by adding an extra consonant.

Epenthesis

A consonant may be added between vowels (

epenthesis In phonology, epenthesis (; Greek ) means the addition of one or more sounds to a word, especially in the beginning syllable ('' prothesis'') or in the ending syllable (''paragoge'') or in-between two syllabic sounds in a word. The word ''epenth ...

) to prevent hiatus. That is most often a semivowel or a glottal, but all kinds of other consonants can be used as well, depending on the language and the quality of the two adjacent vowels. For example, some

non-rhotic Rhoticity in English is the pronunciation of the historical rhotic consonant by English speakers. The presence or absence of rhoticity is one of the most prominent distinctions by which varieties of English can be classified. In rhotic varieti ...

dialects of English often insert to avoid hiatus after non-high word-final or occasionally morpheme-final vowels.

Contraction

In Greek and Latin poetry, hiatus is generally avoided although it occurs in many authors under certain rules, with varying degrees of poetic licence. Hiatus may be avoided by

elision In linguistics, an elision or deletion is the omission of one or more sounds (such as a vowel, a consonant, or a whole syllable) in a word or phrase. However, these terms are also used to refer more narrowly to cases where two words are run toget ...

of a final vowel, occasionally ''prodelision'' (elision of initial vowel), synizesis (pronunciation of two vowels as one without a change in spelling), or contractions such as αει->ᾷ.

Marking

Diaeresis

In Dutch and

French French (french: français(e), link=no) may refer to: * Something of, from, or related to France ** French language, which originated in France, and its various dialects and accents ** French people, a nation and ethnic group identified with Franc ...

, the second of two vowels in hiatus is marked with a

diacritic A diacritic (also diacritical mark, diacritical point, diacritical sign, or accent) is a glyph added to a letter or to a basic glyph. The term derives from the Ancient Greek (, "distinguishing"), from (, "to distinguish"). The word ''diacriti ...

(or ) if otherwise that combination could be interpreted as a diphthong or as having one of the vowels silent. Examples are the Dutch word '' poëzie'' ("poetry") and the French word '' ambiguë'' (feminine form of ''

ambigu Ambigu is an historical French vying game, composed of the characteristic elements of Whist, Bouillotte and Piquet. A Whist pack with the court cards removed is used, and from two to six persons may play. Each player is given an equal number of ...

'', "ambiguous"). This usage is occasionally seen in English (such as ''coöperate'', ''daïs'' and ''reëlect'') but has never been common, and over the last century, its use in such words has been dropped or replaced by the use of a hyphen except in a very few publications, notably '' The New Yorker''.Umlauts in English?
General Questions. Straight Dope Message Board. It is, however, still common in

loanwords A loanword (also loan word or loan-word) is a word at least partly assimilated from one language (the donor language) into another language. This is in contrast to cognates, which are words in two or more languages that are similar because the ...

such as ''naïve'' and ''Noël'' and in the proper names ''Zoë'' and ''Chloë''.

Other ways

In German, hiatus between monophthongs is usually written with an intervening ''h'', as in "to pull"; "to threaten". In a few words (such as ), the ''h'' represents a consonant that has become silent, but in most cases, it was added later simply to indicate the end of the stem. Similarly, in Scottish Gaelic, hiatus is written by a number of digraphs: . Some examples include "river"; "day"; "condition". The convention goes back to the Old Irish scribal tradition, but it is more consistently applied in Scottish Gaelic: (> ). However, hiatus in Old Irish was usually simply implied in certain vowel digraphs (> ), (> ).

Correption

Correption is the shortening of a long vowel before a short vowel in hiatus.

References

Phonetics Vowels