Hem·i·sphere n.
 1. A half sphere; one half of a sphere or globe, when divided by a plane passing through its center.
 2. Half of the terrestrial globe, or a projection of the same in a map or picture.
 3. The people who inhabit a hemisphere.
    He died . . . mourned by a hemisphere.   --J. P. Peters.
 Cerebral hemispheres. Anat. See Brain.
 Magdeburg hemispheres Physics, two hemispherical cups forming, when placed together, a cavity from which the air can be withdrawn by an air pump; -- used to illustrate the pressure of the air. So called because invented by Otto von Guericke at Magdeburg.

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