What does hemisphere mean?
A hemisphere is one of the two halves of a sphere or globe. In everyday geographic use, it commonly means the northern, southern, eastern, or western halves of Earth, often in reference to climate, seasons, or location. The word also has scientific and anatomical uses: astronomers can speak of the hemispheres of the celestial sphere, while neurologists refer to the two halves of the brain as the cerebral hemispheres. Geometrically, a hemisphere is half of a spherical surface or solid. Its usefulness comes from its precision: it describes a three-dimensional half rather than merely a flat semicircle. The word is generally formal or technical, although it is widely understood and frequently appears in educational, geographical, and scientific writing.
nounA hemisphere is one of two halves of a sphere or globe, especially one of the northern, southern, eastern, or western halves of Earth. The term can also refer to one of the brain’s two halves or to half of a celestial sphere.
- One of the two halves of Earth’s surface, especially the northern, southern, eastern, or western hemisphere.
- Either of the two large, roughly symmetrical divisions of the human brain.
- One half of the celestial sphere, as used in astronomical navigation.
- In geometry, one of the two halves of a sphere.
"The island experiences summer in the southern hemisphere while it is winter in the northern hemisphere."
"The northern hemisphere is generally warmer during June and July."
"Research showed that both hemispheres of the brain contributed to the task."
The plural is used when referring to multiple halves of a globe, celestial sphere, brain, or other spherical structure.
"The two hemispheres of the brain communicate through a bundle of nerve fibres."
From the equator to the two halves of the brain, “hemisphere” turns the idea of a sphere into two distinct worlds.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does hemisphere come from?
The English word derives from Modern Latin hemisphaerium, a Latinized form of Greek hemisphairion, meaning “half-sphere.” Greek hemi- means “half,” and sphaira means “sphere”; the word entered English in the late 16th century and later gave rise to forms such as hemispherical. Related English words include sphere, spherical, atmosphere, and biosphere, all sharing the Greek element sphaira.
Related word forms
How hemisphere is actually used
The word is common in geography and scientific contexts. It is more precise than “semicircle,” since a hemisphere is a three-dimensional half of a spherical form. In medicine, the plural “hemispheres” usually refers to the two sides of the brain.
Easily confused with hemisphere
A sphere is the complete round form, whereas a hemisphere is one half of that form.