D defs.my
Entry 1 sense Webster, 1913

Basement

/(bāsment)/ · Base·ment · IPA /ˈbeɪsmənt/
01 n. 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…
  1. 1.
    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.(Arch.) See: Base
Phrases & compounds
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.