|a. a three-dimensional closed surface such that every point on the surface is equidistant from a given point, the centre|
|b. the solid figure bounded by this surface or the space enclosed by it. Equation: (x--a)² + (y--b)² + (z--c)² = r², where r is the radius and (a, b, c) are the coordinates of the centre; surface area: 4πr²; volume: 4πr³/3|
|2.||any object having approximately this shape; globe|
|3.||the night sky considered as a vaulted roof; firmament|
|4.||any heavenly object such as a planet, natural satellite, or star|
|5.||(in the Ptolemaic or Copernican systems of astronomy) one of a series of revolving hollow globes, arranged concentrically, on whose transparent surfaces the sun (or in the Copernican system the earth), the moon, the planets, and fixed stars were thought to be set, revolving around the earth (or in the Copernican system the sun)|
|6.||particular field of activity; environment: that's out of my sphere|
|7.||a social class or stratum of society|
|8.||to surround or encircle|
|9.||to place aloft or in the heavens|
|[C14: from Late Latin sphēra, from Latin sphaera globe, from Greek sphaira]|
A ball-shaped or a globular body.
|sphere (sfîr) Pronunciation Key
A three-dimensional geometric surface having all of its points the same distance from a given point.