pway-er eh-tur-nus
Here's a breakdown:
* pway-er: The "ue" in "puer" makes a similar sound to the "ue" in "due".
* eh-tur-nus: The "ae" in "aeternus" is pronounced as a short "e" sound, similar to the "e" in "pet". The "us" at the end is pronounced like the "us" in "bus".
Note: This pronunciation is based on the Latin origin of the term. Some people may use a different pronunciation depending on their background and language.