empyreal [ɛmˈpɪriəl] a.
1.) Of or pertaining to the empyrean or highest heaven. Also figurative.
2.) Of or pertaining to the sky or visible heaven; celestial.
3.) Sublime, elevated, superior, rare.
4.) In etymological sense: Fiery; composed of or resembling the pure element of fire. Also figurative (Oxford English Dictionary 2nd Edition).
Etymology: Middle English emperiall, from Medieval Latin empyreus, from Late Latin empyrius, fiery, from Greek ἐµπύρος, fiery.
"That glory never shall His wrath or might
Extort from me: to bow and sue for grace
With suppliant knee, and deify His pow'r
Who from the terror of this arm so late
Doubted His empire! That were low indeed,
That were an ignominy and shame beneath
This downfall, since by fate the strength of gods
And this empyreal substance cannot fail,
Since through experience of this great event,
In arms not worse, in foresight much advanced,
We may with more successful hope resolve
To wage by force or guile eternal War
Irreconcilable, to our grand Foe
Who now triumphs, and in th' excess of joy
Sole reigning holds the tyranny of Heav'n."
(Paradise Lost, John Milton, 1667)