Wĕll'-hōle, n.
n. 1. (Arch.) The open space in the middle of a staircase, beyond the ends of the stairs; — called also well, and sometimes limited to the open space in the middle of a winding staircase, or to the opening in the middle of a staircase built round a hollow newel.
Sense 2. A cavity which receives a counterbalancing weight in certain mechanical contrivances, and also for other purposes. Buchanan.