The word "preepistome" is not a commonly-recognized term. However, in terms of pronunciation, it can be broken down into four syllables: pree-ep-ih-stohm. In IPA transcription, this would be [pri-ˈɛpɪstəʊm]. The combination of the "pree" and "epi" sounds in the first two syllables create a smooth transition into the stressed "stohm" sound at the end. Overall, the spelling of "preepistome" seems to match up well with its pronunciation.