Hemisphere (noun)

1. Either half of the Earth or of the celestial sphere as divided by the equator or the celestial equator.
2. Either half of the brain.
3. Either half of a sphere.
4. Either half of a globe.

Origin:

Late latin hemispherium, from greek hemispherion, from hemispherios half-spherical, from hemis- + sphaira sphere.

Examples:

1. The northern hemisphere.
2. The southern hemisphere.
3. The left hemisphere of the brain.
4. The right hemisphere of the brain.
5. The upper hemisphere of a globe.