Syllable nucleus

In phonetics and phonology, 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 onset and end with a coda, but the only part of a syllable that is mandatory is the nucleus. The nucleus and coda form the rime of the syllable.

Diphthongs and triphthongs 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.

Sonorant consonants such as liquids (such as and ) and nasals (such as  and ) 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. Some languages allow other sounds, such as stops, to become nuclei.

Kraoñell ar silabenn Silbenkern Stavingskjerne