(1) An embankment built around a space for defensive purposes
"They stormed the ramparts of the city"
"They blew the trumpet and the walls came tumbling down"
(2) 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"
"The walls were covered with pictures"
(3) A masonry fence (as around an estate or garden)
"The wall followed the road"
"He ducked behind the garden wall and waited"
(4) A layer of material that encloses space
"The walls of the cylinder were perforated"
"The container's walls were blue"
(5) (anatomy) a layer (a lining or membrane) that encloses a structure
(6) Anything that suggests a wall in structure or function or effect
"A wall of water"
"A wall of smoke"
"A wall of prejudice"
"Negotiations ran into a brick wall"
(7) A vertical (or almost vertical) smooth rock face (as of a cave or mountain)
(8) A difficult or awkward situation
"His back was to the wall"
"Competition was pushing them to the wall"
(9) Surround with a wall in order to fortify