An ELT Glossary : Syllable

A word will consist of one or more syllables. Each syllable will be made up of a vowel sound which may or may not have surrounding consonants. For example :Oh!  /əʊ/,  or /ɔː/, and I /aɪ/ are all syllables which  consist of a single vowel sound only. (Whether it is a monopthong, as in or or a diphthong as in the other two examples, makes no difference - it is still considered a single vowel sound).

Alternatively, the vowel may be preceded, followed or both prededed and followed by one or more consonants - eg:    go  /gəʊ/  CV,     art /ɑːt/ VC,     peat /piːt/  CVC,     
through /θruː/ CCV,     slice /slaɪs/ CCVC ,    trust  /trʌst/ CCVCC,      depths  /depθs/ CVCCC

Notice that  it is the phonological realisation which is important in defining the syllable - not the written form. Slice for instance contains two letters which are considered vowels in the written form, but is pronounced as a single syllable - CCVC.

All of the words considered so far are monosyllabic - ie they consist of one syllable only. But obviously, words may consist of more than one syllable, for example:  carpet /kɑːpɪt/  has two (i.e it's bisyllabic);  however  /haʊevə/ has three (i.e it's trisyllabic), and electoral  /elekrəl/ has four. Words with more than three syllables are called polysyllabic words.