Question

“HIC IACET ARTHURUS, REX QUONDAM REXQUE FUTURUS” means

Answer 1

The pharse "HIC IACET ARTHURUS, REX QUONDAM REXQUE FUTURUS" from "The once and future king by T.H White"  means: "Here lies Arthur, king once, king to be".

It was a tomb inscription which promised that even Author was dead, he was going to return one day.

Answer 2

Answer:

This is a Latin phrase meaning "Here lies Arthur, king once, king to be"

Explanation:

This is a phrase is the title of the first book in the series of fantasy books by T. H. White, inspired by the story of King Arthur.  The title comes from an inscription which, according to Thomas Malory's work, Le Morte d'Arthur, was written on the tomb of King Arthur: Hic iacet Arthurus, rex quondam, rexque futurus - Here lies Arthur, king once, king to be."