What does the term "hemisphere" mean?

The term "hemisphere" specifically refers to half of a sphere. This concept is commonly used in various fields, such as geography, where the Earth is often divided into the Northern and Southern Hemispheres, or the Eastern and Western Hemispheres. In mathematics and geometry, a hemisphere is defined as the region created when a three-dimensional sphere is bisected by a plane. This definition makes it clear that the focus is on the idea of dividing the entire sphere into two equal halves, which aligns precisely with the meaning of the term. Understanding this definition can help clarify discussions in both scientific contexts and more general uses of the term, such as in reference to the brain, which can be divided into left and right hemispheres.