| Sound change andalternation |
|---|
| Fortition |
| Dissimilation |
Inphonology,hiatus (/haɪˈeɪtəs/hy-AY-təs) ordiaeresis (/daɪˈɛrəsɪs,-ˈɪər-/dy-ERR-ə-siss, -EER-;[1] also spelleddieresis ordiæresis) describes the occurrence of two separatevowel sounds in adjacentsyllables with no interveningconsonant. When two vowel sounds instead occur together as part of a single syllable, the result is called adiphthong.
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 forNuosu,Bantu languages likeSwahili, andLakota. An example is Swahilieua 'purify' with three syllables.
Many languages disallow or restrict hiatus and avoid it by deleting or assimilating the vowel sound or by adding an extra consonant sound.
A consonant sound may be added between vowels (epenthesis) to prevent hiatus. That is most often asemivowel or aglottal, 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, somenon-rhotic dialects of English often insert/r/ to avoid hiatus after non-high word-final or occasionally morpheme-final vowels.[2]
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 byelision of a final vowel, occasionallyprodelision (elision of initial vowel),synizesis (pronunciation of two vowels as one without a change in spelling), or contractions such as αει->ᾷ.
The first of the two vowels may be converted to aglide to prevent hiatus. This differs from epenthesis as described above, since only one of the two vowels is retained in its original form. For example, inLuganda,/muiko/ is realised as[mwiːk.o].[3] In some cases, this may result in the transfer ofaccent and/orlength from the first to the second vowel, e.g.Icelandicsjá ←*sé + a.[4]
When necessary to indicate a hiatus, either for general clarity or to distinguish it from a diphthong, IPA uses a period ⟨.⟩ to indicate the syllable break. For example,lower can be transcribed ⟨ˈloʊ.ɚ⟩, with a period separating the first syllable,/loʊ/, from the second syllable, ⟨ɚ⟩.
InDutch andFrench, the second of two vowels in hiatus is marked with adiacritic (ortréma) if otherwise that combination could be interpreted as a single vowel (namely either a diphthong, a long vowel, or as having one of the vowels silent, etc.). Examples are the Dutch wordpoëzie ("poetry") and the French wordambiguë (feminine form ofambigu, "ambiguous"). This usage is occasionally seen in English (such ascoöperate,daïs andreëlect) 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, notablyThe New Yorker.[5][6] It is, however, still sometimes seen inloanwords such asnaïve andNoël and in the proper namesZoë andChloë.
InGerman, hiatus betweenmonophthongs is usually written with an interveningh, as inziehen[ˈtsiː.ən] "to pull";drohen[ˈdʁoː.ən] "to threaten";sehen[ˈzeː.ən] "to see". In a few words (such asziehen), theh represents a consonant that has become silent, but in most cases, it was added later simply to indicate the end of the stem. In colloquial speech the examples above drop the second syllable schwa altogether:ziehen[ˈtsiːn],drohen[ˈdʁoːn],sehen[ˈzeːn].
Similarly, inScottish Gaelic, hiatus is written by a number ofdigraphs:bh, dh, gh, mh, th. Some examples includeabhainn[ˈa.ɪɲ] "river";latha[ˈl̪ˠa.ə] "day";cumha[ˈkʰũ.ə] "condition". The convention goes back to theOld Irish scribal tradition, but it is more consistently applied in Scottish Gaelic:lathe (>latha). However, hiatus in Old Irish was usually simply implied in certain vowel digraphsóe (>adha),ua (>ogha).
Correption is the shortening of a long vowel before a short vowel in hiatus.