A group of sounds that are pronounced together, one or more speech sounds forming a single uninterrupted unit of utterance which may be a commonly recognized subdivision of a word or the whole of the word
Articulatorily, it is the minimal articulatory unit of the utterance
Auditorily, it is the smallest unit of perception: the listener identifies the whole of the syllable and after that the sounds which it contains
Phonologically, it is a structural unit which consists of a sequence of one or some phonemes of a language in numbers and arrangements permitted by the given language