What is rex imperator?

As an AI language model, I do not have any specific information about Rex Imperator, as it could refer to various different things depending on the context. The term "Rex Imperator" can be translated as "King-Emperor" or "Emperor-King", and it has been used historically as a title for monarchs in certain countries.

For example, in ancient Rome, "rex" was used to refer to a monarch, while "imperator" was a title granted to successful generals. In 27 BC, Augustus was given the title "imperator" by the Roman Senate, and he later became known as "Rex Imperator Augustus" or "Emperor Caesar Augustus".

In more recent times, "Rex Imperator" was used as the motto of various European royal families, including the kings of Belgium and the Netherlands, and as the name of a British Thoroughbred racehorse. But without a specific context, it is difficult to provide more specific information on "Rex Imperator."