Subrealm

Subrealm is a term used in fantasy, science fiction, and related narrative and game design contexts to denote a distinct realm that exists as a subdivision of a larger cosmology, such as a universe, plane, or world. A subrealm is typically a self-contained region with its own geography, ecosystems, and often its own set of physical laws, magical rules, or technological limitations. Access to a subrealm is usually through specific gateways, catalysts, or conditions, and travel between subrealms may be regulated by factions or governed by rare artifacts.

In fiction and gaming, subrealms function as settings for exploration, lore development, and plot mechanisms. They can serve as transitional spaces between major arcs or as environments with unique hazards, inhabitants, and quests. Subrealms may be described as temporary or permanent, cosmically separate yet connected to the larger world, and they sometimes reflect thematic contrasts—such as order versus chaos, life versus death, or the material versus the ethereal.

Although related to the broader idea of a plane or dimension, subrealms are typically considered parts of the same overarching cosmos rather than independent, causally separate worlds. They are often conceived as pockets or subdivisions within a single reality, offering structured variation within a multiverse. The term is common in worldbuilding, role-playing games, and narrative theory as a way to describe layered or hierarchical space within a single setting.

See also: plane, dimension, pocket dimension, multiverse, realm.