Dictionary.com's Word of the Year is...
mid-15c., "sphere, globe, something spherical or circular," from Old French orbe "orb, globe" (13c.) and directly from Latin orbem (nominative orbis) "circle, disk, ring, hoop, orbit," probably related to orbita "wheel track, rut," of unknown origin. Watkins suggests a connection with the root of orchid.
A three-dimensional extension of a word originally describing two-dimensional shapes. Astronomical sense is in reference to the hollow spheres that carried the planets and stars in the Ptolemaic system. As a verb from c.1600. Orb weaver spider is first recorded 1889.
emblem of royal power, usually made of precious metal and jewels and consisting of a sphere surmounted by a cross. The ball as a symbol of the cosmos, or of the universe as a harmonious whole, is derived from the ancient Romans, who associated it with Jupiter and, hence, with the emperor as his earthly representative.