\Sub*struc"tion\, n. [L. substructio, fr.
substruere, substructum, to build beneath; sub under +
struere to build.] (Arch.)
Underbuilding; the foundation, or any preliminary structure
intended to raise the lower floor or basement of a building
above the natural level of the ground.
      It is a magnificent strong building, with a
      substruction very remarkable.            --Evelyn.