onsetnucleuscoda

Onset-nucleus-coda is a basic unit of syllable structure in phonology. The model divides a syllable into three subparts: the onset, the nucleus, and the coda. The onset consists of the initial consonant(s); the nucleus is the syllable’s core, typically a vowel; the coda comprises the final consonant(s). In many languages the nucleus is a vowel, but some languages allow syllabic consonants to serve as the nucleus, and some consonant clusters may belong to the onset or the coda.

Not all languages require both onset and coda. An open syllable has no coda (as in CV), while a closed syllable has a coda (as in CVC). Onsets may be single consonants or clusters; codas likewise may be simple or complex. English provides many examples of varied structures: cat has onset /k/, nucleus /æ/, coda /t/; plant has onset /pl/, nucleus /æ/, coda /nt/; go has onset /ɡ/, nucleus /oʊ/, with no coda.

The onset-nucleus-coda framework supports cross-linguistic analysis of syllable inventories and phonotactics. It is used to describe permissible consonant clusters, syllable weight, and stress patterns within many phonological theories. The concept is widely applied in descriptive phonology, language teaching, and computational tools for syllabification and automatic analysis of syllables across languages. While the exact realizations vary by language, the tripartite structure provides a common reference point for comparing how different languages assemble syllables from consonants and vowels.