the nucleus (sometimes called peak) is the
central part of the syllable,
most commonly a vowel.
In addition to a nucleus, a syllable may begin with an
and end with a coda,
but in most languages the only part of a syllable that
is mandatory is the nucleus. The nucleus and coda form
of the syllable.
can also serve as the nucleus. Syllables with short
vowels as nuclei are sometimes referred to as "light
syllables" while syllables with long
vowels, diphthongs, or triphthongs as nuclei are referred
to as "heavy syllables"; see Syllable
weight for more discussion.
consonants such as liquids
(such as [r]
(such as [m]
can serve as the nucleus if there is no vowel.
The nucleus of the last syllable in the final example
at right is an example of a sonorant nucleus.
In a small number of languages, the onset may also be
mandatory, so that vowel-initial syllables are not found.
There are also a few languages such as Nuxalk
and some dialects of Berber,
which have some obstruent-only
words. It is difficult to divide such words into syllables
using conventions from other languages; it may be that
the concept of 'syllable' doesn't apply, or that syllabic
nuclei are optional in these languages.