noun.
In fortification, a facing to a wall or bank. as of a scarp or parapet; a retaining wall (which see, under retaining).
noun.
In civil engineering, a retaining wall or breastwall; also, any method of protecting banks or the sides of a cut to preserve them from erosion, as the sheathing of a river-bank with mats, screens, or mattresses.
noun.
In architecture, any facing of stone, metal, or wood over a less sightly or durable substance or construction.