Sphere (noun)

1. A three-dimensional geometrical shape, where every point on the surface of the shape is equidistant from the center.
2. A particular area of activity or influence.
3. A celestial body, such as the earth or the moon, that is in the shape of a sphere.

Origin:

The word "sphere" comes from the old french word "esfera" which is derived from the latin word "sphæra" which means "a ball" or "a globe" and it first recorded use in the english language in the 14th century.

Examples:

1. The earth is a sphere.
2. The sphere is a fundamental shape in geometry.
3. The sphere of influence of a country is the area of the world where that country exerts the most influence.
4. The sphere of influence of the company extends globally.
5. The sphere of influence of the politician is mainly limited to his home state.