1. An object similar in shape to a ball.
2. In mathematics, a three-dimensional closed surface consisting of all points that are at a given distance from a center.
3. A solid figure bounded by a sphere, or the volume it encloses.
4. A field of knowledge, interest, or activity.
5. An area of control or influence: "The student took no interest in matters beyond her sphere of knowledge."
6. A level or group within a society or a particular social world, stratum of society, or walk of life: "His social sphere was very limited."
7. An astronomical object; such as, a planet, moon, or star.
8. In early astronomical theory, a revolving concentric transparent shell on which the sun, moon, planets, and stars were thought to be fixed as they moved around the earth.
9. The sky, appearing as a hemisphere to an observer; for example, the sphere of the heavens.
10. Etymology: from Greek σφαῖρα, sphaira, "globe, ball" or a perfectly round geometrical object in three-dimensional space; such as, the shape of a round ball.

1. To form into a round shape.
2. To put in or as if in a global zone.
3. To surround or to encompass.

1. The imaginary orbit around the Earth: The sun, moon, stars, and planets appear to be placed on the celestial sphere.
2. The imaginary shell formed by the sky: The celestial sphere is usually, represented as an infinite circle, the center of which is the observer's position.

Also known as the "geodesic dome", a dome or structure: A geodesic sphere roughly approximates a hemisphere constructed of many light, straight structural elements in tension, arranged in a framework of triangles to reduce stress and weight.

The region of the interstellar medium surrounding the earth to a radius of roughly 500 light years.

1. A spark gap between two equal-diameter spherical electrodes.
2. A spark gap in which the spark passes between two polished metal bails.

An instrument designed to measure high voltages by determining the distance between two metal spheres at which a spark will jump.

1. The distance within which the potential energy arising from mutual attraction of two molecules is not negligible with respect to the molecules' average thermal energy at room temperature.
2. In physical chemistry, the area between two molecules within which the energy generated by their mutual attraction is significant enough to be distinguished from the average energy of other molecules in the system.

An area of the world dominated politically or economically by a country, or certain countries.

In crystallography, a construction for considering conditions for diffraction in terms of the reciprocal rather than the real lattice.

It is a sphere with the incident beam along a diameter. The origin of the reciprocal lattice is positioned at the point where the incident beam emerges from the sphere.

Whenever a reciprocal lattice point touches the surface of the sphere, the conditions for a diffracted (or reflected) beam are satisfied.

An instrument for measuring the total luminous flux of a lamp or luminaire; the source is placed inside a sphere whose inside surface has a diffusely reflecting white finish, and the light reflected from this surface onto a window is measured by an ordinary photometer.

A concept derived from Greek astronomy in which the region of the cosmos from the earth to the moon, consists of the four classical elements: earth, water, air, and fire.

Beginning with the moon, up to the limits of the universe, everything is made of ether.