A half sphere; one half of a sphere or globe, when divided by a plane passing through its center.
- A half of a sphere bounded by a great circle.
- A half of a symmetrical, approximately spherical object as divided by a plane of symmetry.
- Either half of the celestial sphere as divided by the ecliptic, the celestial equator, or the horizon.
- Either the northern or southern half of the earth as divided by the equator or the eastern or western half as divided by a meridian.
- Anatomy Either of the lateral halves of the cerebrum; a cerebral hemisphere.