orbis

Orbis, orbis is masculine, third declension and an i-stem: genitive plural orbium, though the ablative singular is orbe, not orbi. The basic sense is a ring or a disc, and from there a wheel, a coil of a snake, the socket of an eye, a round shield, a circuit of years.

The standard phrase for "the world" is orbis terrarum, the circle of the lands, which reflects the map the Romans actually drew: a disc of land with the ocean round the edge. In later and ecclesiastical Latin orbis alone does the same job, and the papal blessing urbi et orbi plays the two words off each other. English orb, orbit and exorbitant (out of the track) all descend from it.