A unit of pronunciation typically larger than a single sound and smaller than a word. A word may be pronounced ‘syllable at a time’, and a good dictionary will indicate where these syllabic divisions occur in writing, thus providing information about how a word may be hyphenated. The notion of syllable, in short, is very real to native-speakers, and is often used in a quasi-technical sense in everyday conversation. Syllabification is the term which refers to the division of a word into syllables; resyllabification refers to a reanalysis which alters the location of syllable boundaries. A word containing a single syllable is called a monosyllable; if it contains more than one, the term polysyllable is used (or monosyllabic word / polysyllabic word respectively).

Phonological views of the syllable focus on the ways sounds combine in individual languages to produce typical sequences. Here two classes of sounds are usually established: sounds which can occur on their own, or at the centre of a sequence of sounds, and sounds which cannot occur on their own, or which occur at the edges of a sequence of sounds. The former include such sounds as [i],[a],[u], etc., and are generally referred to as vowels; the latter include such sounds as [p],[g],[f],[tʃ],etc., and are generally referred to as consonants. A consonant-vowel (CV) sequence is a pattern which seems to be found in all languages: because the syllable is not ‘closed’ by another consonant, this type of syllable is often called an open syllable type. A CVC pattern is also very common in English. In such a case, the following terminology is widely used:

the opening segment of a syllable = the onset,

the closing segment of the syllable = the coda,

the central segment of the syllable = the centre or nucleus.

A useful collective term for the opening and closing segments is the margins (or edges) of the syllable. In metrical phonology, the nucleus and coda are viewed as a single constituent of syllable structure, called the rhyme (or rime), and syllables are distinguished phonologically in terms of their weight.

In the distinctive feature theory of phonology proposed by Chomsky and Halle, syllabic is used to replace the earlier term ‘vocalic’, referring to all segments constituting a syllabic nucleus. Vowels, liquids and nasals would be [+syllabic] ([+syll]); all other segments would be [-syll].