An abstract sphere of infinite radius which serves as the imaginary backdrop for celestial objects, and of which the visible sky is one hemisphere.
the figure of the universe as an imaginary sphere whose center is the Earth
The region of pure light and fire; the highest heaven, where the pure element of fire was supposed by the ancients to exist: the same as the ether, the ninth heaven according to ancient astronomy, and Dante's poem.
Of the sky or the heavens; celestially refined.