• (n.) 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.
Sub·struc'tion noun [ Latin substructio , from substruere , substructum , to build beneath; sub under + struere to build.] (Architecture) Underbuilding; the foundation, or any preliminary structure intended to raise the lower floor or basement of a building a...
In architecture a substruction is the under building, foundation, or any preliminary structure intended to raise the lower floor or basement of a building above the natural level of the ground.
a foundation or substructure.