underworks

/ˈʌndərwɜːrks/
noun
  1. The parts of a structure or machine that are underneath or support it; the foundation or substructure.
    • The mechanic crawled beneath the car to examine the underworks for rust.
    • The bridge's underworks were inspected for cracks after the earthquake.
    • The building's underworks include a deep concrete foundation and steel beams.
What does "underworks" mean? | whatsthatwordmean | whatsthatwordmean