noun
- a floor or level below the basement of a building
Examples
- The old hospital had a subbasement that housed the morgue.
- Storage rooms were located in the subbasement of the office building.
- The elevator descended to the subbasement parking garage.
- Mechanical equipment was installed in the subbasement to save space.
- The subbasement flooded during the heavy rains last spring.
- Access to the subbasement required a special security card.