Base"ment (?), n. [F. soubassement. Of uncertain origin. Cf. Base, a., Bastion.] Arch.
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, n., 3 (a).) Hence: The rooms of a ground floor, collectively.
Basement membrane Anat., a delicate membrane composed of a single layer of flat cells, forming the substratum upon which, in many organs, the epithelioid cells are disposed.
© Webster 1913.