1. a level or floor below the main level, especially in a building or structure
2. a subdivision or secondary level within a larger category or system

Examples

• The parking garage has three sublevels beneath the ground floor.
• Emergency exits are located on each sublevel of the building.
• The game features multiple sublevels within each main stage.
• Access to the sublevel requires a special security card.
• The organizational chart shows various sublevels of management.
• Storage rooms are located on sublevel B2.