hemisphere

Etymology

From Latin hemisphaerium, from Ancient Greek ἡμισφαίριον (hēmisphaírion), from ἡμι- (hēmi-, “half”) + σφαῖρα (sphaîra, “sphere”). Equivalent to hemi- + sphere. Displaced native Old English healftrendel (literally “half-sphere”).

noun

1. (astronomy, astrology) Half of the celestial sphere, as divided by either the ecliptic or the celestial equator .
2. (figurative) A realm or domain of activity .
3. (geography) Half of the Earth, such as the Northern Hemisphere, Southern Hemisphere, Western Hemisphere or Eastern Hemisphere, Land Hemisphere, Water Hemisphere etc. .
4. (geometry) Any half-sphere, formed by a plane intersecting the center of a sphere. .
5. (cartography) A map or projection of a celestial or terrestrial hemisphere .
6. (anatomy) Either of the two halves of the cerebrum. .