1. an underlying or supporting structure, especially the foundation of a building
2. the basic framework or underlying system that supports something
Usage: often used figuratively

Examples

• The bridge’s substructure was built to withstand earthquakes.
• Engineers inspected the building’s substructure for damage.
• The concrete substructure supports the entire weight of the tower.
• A strong educational substructure is essential for student success.
• The company’s financial substructure needed restructuring.
• Workers poured concrete for the substructure of the new hospital.
• The social substructure of the community influences local politics.