Complex sentence: The name "Vatican" has often been thought to derive from the Latin "vates", meaning "seer, soothsayer", though this is uncertain and it is also possible that "Vaticanus" comes from an unrelated Etruscan loan-word.
Split into simpler sentences: The name "Vatican" has often been thought to derive from the Latin "vates", meaning "prophet, seer". It is also possible that "Vaticanus" comes from an unrelated Etruscan loan-word.