basement

noun

1. A floor of a building below ground level.

   “Turning back, then, toward the basement staircase, she began to grope her way through blinding darkness, but had taken only a few uncertain steps when, of a sudden, she stopped short and for a little stood like a stricken thing, quite motionless save that she quaked to her very marrow in the grasp of a great and enervating fear.”

2. (abbreviation, alt-of, ellipsis)A floor of a building below ground level.
3. A mass of igneous or metamorphic rock forming the foundation over which a platform of sedimentary rocks is laid.
4. (informal)Last place in a sports conference's standings.