underareas

Underareas is a term used across disciplines to refer to subregions associated with or contained within a larger area, typically indicating a location beneath the surface or inside a larger boundary. It is not an established technical term, and definitions vary by field.

In urban planning and architecture, underareas describe subterranean spaces such as basements, tunnels, transit corridors, or underground shopping concourses, and may include utility tunnels and storage levels. They are considered in zoning, safety, and infrastructure planning.

In geology and mining, underareas denote subsurface zones beneath the surface footprint that contain rock formations, ore bodies, or groundwater, mapped for exploration and resource assessment. They are distinguished from overlying surface areas and are analyzed with geophysical methods.

In media and world-building, underareas can describe hidden or lower layers of a fictional setting, offering space for lore, infrastructure, or narrative development.

In mathematics, the standard concept is area under a curve, not typically called underarea; usage would be metaphorical. Related terms include subarea, subsurface, basement, and underground.