Definition of "Wall" :
noun: an embankment built around a space for defensive purposes
"They blew the trumpet and the walls came tumbling down."
noun: an architectural partition with a height and length greater than its thickness; used to divide or enclose an area or to support another structure
"The south wall had a small window."
noun: a masonry fence (as around an estate or garden)
"The wall followed the road."
noun: a layer of material that encloses space
"The walls of the cylinder were perforated."
noun: (anatomy) a layer (a lining or membrane) that encloses a structure
noun: anything that suggests a wall in structure or function or effect
"A wall of water."
noun: a vertical (or almost vertical) smooth rock face (as of a cave or mountain)
noun: a difficult or awkward situation
"His back was to the wall."
verb: surround with a wall in order to fortify