The hemisphere of the Earth to the east of the Greenwich Meridian (zero degree longitude) and west of 180 degrees longitude (approximately the International Date Line).

The hemisphere of the Earth (or any celestial body) to the north of its equator.

The hemisphere of the Earth (or any celestial body) to the south of its equator.

plural of Southern Hemisphere

(historical) Either of a pair of large copper hemispheres, with mating rims, that were used to demonstrate the power of atmospheric pressure. When the rims were sealed with grease and the air was pumped out, the sphere contained a vacuum and could not be pulled apart even by teams of horses.

plural of Magdeburg hemisphere

Shaped into a hemisphere or hemispheres. / Having a (dominant) cerebral hemisphere of a specified kind.

(neurosurgery) Surgical removal of a hemisphere of the brain, usually performed to control otherwise uncontrollable epilepsy.

plural of hemispherectomy