[beys-muh nt]
See more synonyms for basement on
  1. a story of a building, partly or wholly underground.
  2. (in classical and Renaissance architecture) the portion of a building beneath the principal story, treated as a single compositional unit.
  3. the lowermost portion of a structure.
  4. the substructure of a columnar or arched construction.

Origin of basement

First recorded in 1720–30; base1 + -ment Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for basement


    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
  1. the foundation or substructure of a wall or building
  2. 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
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for basement

"lowest story of a building except the cellar," 1730, from base (n.) + -ment.

Online Etymology Dictionary, © 2010 Douglas Harper