The spelling of the word "diether" can be quite tricky for those unfamiliar with it. Phonetically, it can be broken down into three syllables: /ˈdaɪθər/. The first syllable, "di," is pronounced with a long "i" sound, while the second syllable is pronounced with a soft "th" sound. The final syllable is pronounced with the schwa sound, which can sometimes sound like an "uh" sound. Putting it all together, "diether" is pronounced as /ˈdaɪθər/.
The etymology of the word "diether" requires further clarification, as it is not a recognized English word. It is possible that the term you are referring to is a proper noun or a name of someone. If "diether" is a person's name, its etymology would depend on its cultural and linguistic origins. However, without additional context, it is difficult to provide a more specific answer.