(a) The cosmos, composed of hollow concentric revolving spheres surrounding the earth; ~ of the firmament; (b) the outermost sphere of the cosmos, the primum mobile, regulating the motion of the other spheres, variously numbered the eighth or ninth and thought by some astronomers to contain the fixed stars; ~ coverant, ~ of heven; (c) the sphere of the fixed stars; (d) one of the seven planetary spheres; mid-dai ~ [see mid-dai n. 3.(b)]; (e) one of the three spheres in heaven outside the cosmos; (f) pl. the cosmic spheres beyond the earth extending from the planetary spheres on to the heavenly spheres; often, the seven planetary spheres, the sphere of the fixed stars, and the primum mobile; (g) one of the concentric globes formed by the elements earth, water, fire, and air; also, the totality of these globes; (h) tretise of the ~, De Sphæra, by John of Sacrobosco.

(a) A globe serving as a model of the cosmos; ~ of pictagoras, pictagoras ~, such a model used in divination; (b) a representation of one of the spheres used as a point of reference in astronomical calculations.

(a) A spherical object, a ball, a globe, or an orb; (b) a circle; a circular diagram; ?also, a halo; (c) geom. a solid figure with all points equidistant from the center, a sphere.