Answer: aether

AnswerCrossword Clue
AETHER

What Olympians breathed

AETHER

Air of the Olympian gods

AETHER

Upper regions of space: Var.

AETHER
Heavens; clear sky: Var.
AETHER
Greek god of the upper air
AETHERHeavens: Var.
AETHERMaterial beyond the terrestrial plane, in medieval science
AETHERThe heavens