orb.
1. Globe surmounted by a cross, an emblem of power and sovereignty, often placed on top of the lantern of a cupola, pinnacle, or spire.

2. Spherical termination or finial on a pedestal or pier.

3. Circular knot of flowers or herbs (boss) fixed at the intersection of ribs in a Gothic vault, serving to conceal the junction of the mouldings and act as an abutment to them.

4. Medieval term for a blind panel in tracery, especially in Perpendicular work.

orb / ôrb/ • n. a spherical body; a globe. ∎  a golden globe surmounted by a cross, forming part of the regalia of a monarch. ∎ poetic/lit. a celestial body. ∎  (usu. orbs) poetic/lit. an eyeball; an eye. ∎  Astrol. a circle of up to 10° radius around the position of a celestial object: within an orb of 1° of Mars.• v. [tr.] poetic/lit. encircle; enclose. ∎  form (something) into an orb; make circular or globular.

orb †(old astron.) hollow sphere surrounding the earth; †circle, ring; heavenly body XVI; eyeball, eye XVII; cross-surmounted globe of the regalia XVIII. — L. orbis ring, round surface, disc.
Hence orbed (-ED2) XVI. So orbicular circular, spherical. XVI. — late L. orbiculāris, f. L. orbiculus, dim. of orbis; see -CULE, -AR.

orb a golden globe surmounted by a cross, forming part of the regalia of a monarch. Recorded from late Middle English in the sense ‘circle’, the word comes from Latin orbis ‘ring’.

Orb

a collective whole; a circle of things or people. See also ball, globe, sphere.

Examples: orb of order and form, 1603; of soldiers; of witnesses, 1866.