from the GNU version of the Collaborative International Dictionary of English
- adj. the mass of materials used in filling up the space between two walls, or between the inner and outer faces of a wall, or upon the haunches of an arch or vault.
- n. See under Back, a.
from The Century Dictionary and Cyclopedia
- n. Rough masonry forming the back of a wall.
- n. The filling in again of a place from which earth has been removed; the earth so filled in.
Sorry, no etymologies found.