Primarily in Austroasiatic languages (also known as Mon–Khmer), in a typical word a minor syllable is a reduced (minor) syllable followed by a full tonic or stressed syllable. The minor syllable may be of the form or, with a reduced vowel, as in colloquial Khmer, or of the form with no vowel at all, as in Mlabri 'navel' (minor syllable ) and 'underneath' (minor syllable ), and Khasi kyndon 'rule' (minor syllable ), syrwet 'sign' (minor syllable ), kylla 'transform' (minor syllable ), symboh 'seed' (minor syllable ) and tyngkai 'conserve' (minor syllable ). This iambic pattern is sometimes called sesquisyllabic (lit. 'one and a half syllables'), a term coined by the American linguist James Matisoff in 1973 (Matisoff 1973:86). Although the term may be applied to any word with an iambic structure, it is more narrowly defined as a syllable with a consonant cluster whose phonetic realization is [CǝC].

In historical linguistics

Sometimes minor syllables are introduced by language contact. Many Chamic languages as well as Burmese have developed minor syllables from contact with Mon-Khmer family. In Burmese, minor syllables have the form, with no consonant clusters allowed in the syllable onset, no syllable coda, and no tone. Some reconstructions of Proto-Tai and Old Chinese also include sesquisyllabic roots with minor syllables, as transitional forms between fully disyllabic words and the monosyllabic words found in modern Tai languages and modern Chinese.