The pre-Christmas period, which is bursting with kitsch and pomp, is exactly the right time to clarify the origin of “pompous”. And the story is at least as spectacular as the word itself.
The noun “pomp” was already used in Middle High German. The word “pompous” only really had its heyday in the 17th century (that’s not surprising, after all, that’s exactly when the Baroque era can be located). Its revival was influenced by the French “pompeux”, which was borrowed from the Latin “pomposus”. This in turn has the Greek “pompe” as its basis, which meant something like “escort, festive procession”.