Hiatus (linguistics)

In phonology, hiatus (/haɪˈeɪtəs/; Latin: [hɪˈaːtʊs] "gaping") or diaeresis (/daɪˈɛrᵻsᵻs/ or /daɪˈiːrᵻsᵻs/, from Ancient Greek διαίρεσις diaíresis "division") refers to two vowel sounds occurring in adjacent syllables, with no intervening consonant. When two adjacent vowel sounds occur in the same syllable, the result is instead described as a synaeresis.

The English words hiatus and diaeresis themselves each contain a hiatus between the first and second syllables.

Some languages do not have diphthongs, except optionally in rapid speech, or have a limited number of diphthongs but also numerous vowel sequences which cannot form diphthongs and thus appear in hiatus. This is the case of Japanese, Bantu languages such as Swahili and Zulu, and Polynesian languages such as Hawaiian and Māori. Examples are Japanese aoi 'blue/green', Swahili eua 'to purify', and Hawaiian aea 'to rise up', all of which are three syllables.

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