#structural universe
- Cosmic void — A neologistic astronomical term used theoretically or hypothetically to describe a state or cosmic space characterized by the complete absence of galaxies; a vast region in the deep universe devoid of organized stellar structures or galactic systems.
- Arda — A proper name designating a major river in the Balkan Peninsula, a tributary of the Maritsa, rising in the Rhodope Mountains (Bulgaria) and flowing through northeastern Greece and a section of Turkey. In the context of J.R.R. Tolkien's high-fantasy legendarium, the term represents the mystical name of the entire created Earth, including continents and seas, configured as the structural realm for the history of Elves and Men.