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
Any half-sphere, formed by a plane intersecting the center of a sphere. .
A realm or domain of activity .
A map or projection of a celestial or terrestrial hemisphere .
Half of the celestial sphere, as divided by either the ecliptic or the celestial equator .
Half of the Earth, such as the Northern Hemisphere, Southern Hemisphere, Western Hemisphere or Eastern Hemisphere, Land Hemisphere, Water Hemisphere etc. .
Either of the two halves of the cerebrum. .