1. In masonry and bricklaying, the side of a masonry unit on which it lies in the course of the wall the underside when placed horizontally.
2. The layer of mortar on which a masonry unit is set. 3. The lower surface or side of a slate.
4. To set a glass pane in place with putty.
5. In layered stone used for building, a surface parallel to the stratification.
6. A layer (stratum) of rock between two bedding planes.