understructure

/ˈʌndərˌstrʌktʃər/
noun
  1. A supporting structure or foundation built beneath something; the base that supports a building, bridge, or other construction.
    • The bridge's understructure was reinforced after the earthquake.
    • Engineers inspected the understructure of the stadium for cracks.
    • The house's understructure includes a concrete foundation and steel beams.
  2. The underlying system or framework that supports an organization, process, or idea.
    • The company's understructure of policies and procedures kept it running smoothly.
    • The understructure of the argument was based on faulty data.
    • A strong educational understructure is essential for a successful career.