Definition

• n. - A body or space contained under a single surface, which in every part is equally distant from a point within called its center.
• n. - Hence, any globe or globular body, especially a celestial one, as the sun, a planet, or the earth.
• n. - The apparent surface of the heavens, which is assumed to be spherical and everywhere equally distant, in which the heavenly bodies appear to have their places, and on which the various astronomical circles, as of right ascension and declination, the equator, ecliptic, etc., are conceived to be drawn; an ideal geometrical sphere, with the astronomical and geographical circles in their proper positions on it.
• n. - In ancient astronomy, one of the concentric and eccentric revolving spherical transparent shells in which the stars, sun, planets, and moon were supposed to be set, and by which they were carried, in such a manner as to produce their apparent motions.
• n. - The extension of a general conception, or the totality of the individuals or species to which it may be applied.
• n. - Circuit or range of action, knowledge, or influence; compass; province; employment; place of existence.