The Seen

The normal, physical world, as opposed to the mysterious and hidden realm of the Wraith-world. A significant effect of the One Ring, and at least some of the other Rings of Power, was to draw their wearers from the world of the Seen into that of the Unseen. Those entirely under power of such Rings were lost permanently to the Seen World, as with the Ringwraiths, whose forms were invisible in the Seen World, but appeared as pale wraiths to those who crossed into their own realm.

Other beings existed by their nature in both the Seen and the Unseen domains. Our only explicit example is in the case of the High Elf Glorfindel, but Gandalf implies (in the reference quoted above) that this was true of all those who had dwelt in Aman. If this is true, then this would include those of the Noldor who had returned to Middle-earth (notably Galadriel) as well as the Wizards, who had themselves come from beyond the Great Sea.