Wall

noun

1. Any of various permanent upright constructions having a length much greater than the thickness and presenting a continuous surface except where pierced by doors, windows, etc.: used for shelter, protection, or privacy, or to subdivide interior space, to support floors, roofs, or the like, to retain earth, to fence in an area, etc.

2. Usually walls. A rampart raised for defensive purposes.

3. An immaterial or intangible barrier, obstruction, etc., suggesting a wall.

4. A wall-like, enclosing part, thing, mass, etc.:

5. An embankment to prevent flooding, as a levee or sea wall.

6. The outermost film or layer of structural material protecting, surrounding, and defining the physical limits of an object.