phonotactics

/ˌfoʊnəˈtæktɪks/
noun
  1. The set of rules in a language that describe which sounds can appear together and in what order.
    • Learning the phonotactics of a new language helps you sound more natural when speaking.
    • In English, phonotactics explains why 'spl' can start a word like 'splash' but 'psl' cannot.
    • The word 'ng' is not allowed at the beginning of English words because of phonotactics.