Syllable onset

A syllable onset is the constituent preceding the syllable nucleus within a syllable. It may contain one consonant or a consonant cluster, and some syllables have no onset. A language's phonotactics constrains which combinations can occupy that position.^[ref]

In “cat”, [k] is a simple syllable onset; in “stay”, [st] forms a cluster before the vowel. A vowel-initial pronunciation can instead begin directly with the syllable nucleus. This is a statement about spoken structure: the number of written initial letters need not equal the number of onset consonants, and no physical pause is required at every syllable boundary.