basement

[ beys-muh nt ]
/ ˈbeɪs mənt /

noun

a story of a building, partly or wholly underground.
(in classical and Renaissance architecture) the portion of a building beneath the principal story, treated as a single compositional unit.
the lowermost portion of a structure.
the substructure of a columnar or arched construction.

Origin of basement

First recorded in 1720–30; base1 + -ment

British Dictionary definitions for basement

basement
/ (ˈbeɪsmənt) /

noun

  1. a partly or wholly underground storey of a building, esp the one immediately below the main floorCompare cellar
  2. (as modifier)a basement flat
the foundation or substructure of a wall or building
geology a part of the earth's crust formed of hard igneous or metamorphic rock that lies beneath the cover of soft sedimentary rock, sediment, and soil