In phonetics and phonology, a syllable onset is the part of a syllable that precedes the syllable nucleus.

Syllable structure

The segmental structure of a syllable begins with an onset, followed by a rime or final.

syllable: C₁(C₂)V₁(V₂)(C₃)(C₄) = onset: C₁(C₂) + rime: V₁(V₂)(C₃)(C₄)

syllable: V₁(V₂)(C₃)(C₄) = onset: Ř (null) + rime: V₁(V₂)(C₃)(C₄)

(C = consonant, V = vowel, optional components are in parentheses.)

Depending on the phonotactics of a language, the onset can consist of a single consonant or a consonant cluster. If a syllable begins with a vowel or another syllabic sonorant, then the syllable is said to have no onset, or a null onset. (Most languages allow this possibility.) The terms null initial and zero initial are used as well.

br:Penn ar silabenn es:Ataque silábico ja:?? nn:Stavingsframlyd zh:??