Pronunciation: (bās'munt), [key]
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.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.