The highest heaven, the pure realm of fire or light imagined beyond the sky's blue. In medieval and Renaissance cosmology, this was the dwelling-place of the divine, an upper world of mind and myth where visibility gives way to radiance.

Heavenly; pertaining to that highest, radiant realm.

From Medieval Latin empyreus, from Greek empyrios “in fire,” from en- “in” + pyr “fire.” The word preserves a cosmos built of elements and ascent: heaven not as distance, but as brightness intensified.