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.

<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.

(01 Mar 1998)