Answer: aether

AnswerCrossword Clue
AETHERWhat Olympians breathed
AETHERAir of the Olympian gods
AETHERUpper regions of space: Var.
AETHERHeavens; clear sky: Var.
AETHERGreek god of the upper air
AETHERHeavens: Var.
AETHERMaterial beyond the terrestrial plane, in medieval science
AETHERThe heavens
aetherthe upper region of the atmosphere
aetherthe material thought by the ancients to fill the heavens
aetherthe ancient Greek personification of the clear upper air of the sky
aetherthe upper regions of space; the heavens