the outer wall of the ground story of a building, or of a part of that story, when treated as a distinct substructure. (see base, 3) Hence: The rooms of a ground floor, collectively.
(Science: anatomy) basement membrane, a delicate membrane composed of a single layer of flat cells, forming the substratum upon which, in many organs, the epithelioid cells are disposed.
Origin: f. Soubassement. Of uncertain origin. Cf. Base, Bastion.