1. [n]  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. [n]  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. [n]  a masonry fence (as around an estate or garden); "the wall followed the road"; "he ducked behind the garden wall and waited"
4. [n]  a layer of material that encloses space; "the walls of the cylinder were perforated"; "the container's walls were blue"
5. [n]  (anatomy) a layer (a lining or membrane) that encloses a structure; "stomach walls"
6. [n]  anything that suggests a wall in structure or effect; "a wall of water"; "a wall of smoke"; "a wall of prejudice"
7. [n]  a vertical (or almost vertical) smooth rock face (as of a cave or mountain)
8. [n]  a difficult or awkward situation; "his back was to the wall"; "competition was pushing them to the wall"
9. [v]  surround with a wall in order to fortify

Wall
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1. \Wall\, n. (Naut.)
   A kind of knot often used at the end of a rope; a wall knot;
   a wale.
   {Wall knot}, a knot made by unlaying the strands of a rope,
      and making a bight with the first strand, then passing the
      second over the end of the first, and the third over the
      end of the second and through the bight of the first; a
      wale knot. Wall knots may be single or double, crowned or
      double-crowned.
   

2. \Wall\, n. [AS. weall, from L. vallum a wall, vallus a
   stake, pale, palisade; akin to Gr. ? a nail. Cf. {Interval}.]
   1. A work or structure of stone, brick, or other materials,
      raised to some height, and intended for defense or
      security, solid and permanent inclosing fence, as around a
      field, a park, a town, etc., also, one of the upright
      inclosing parts of a building or a room.
            The plaster of the wall of the King's palace. --Dan.
                                                  v. 5.
   2. A defense; a rampart; a means of protection; in the
      plural, fortifications, in general; works for defense.
            The waters were a wall unto them on their right
            hand, and on their left.              --Ex. xiv. 22.
            In such a night, Troilus, methinks, mounted the
            Troyan walls.                         --Shak.
            To rush undaunted to defend the walls. --Dryden.
   3. An inclosing part of a receptacle or vessel; as, the walls
      of a steam-engine cylinder.
   4. (Mining)
      (a) The side of a level or drift.
      (b) The country rock bounding a vein laterally. --Raymond.
   Note: Wall is often used adjectively, and also in the
         formation of compounds, usually of obvious
         signification; as in wall paper, or wall-paper; wall
         fruit, or wall-fruit; wallflower, etc.
   {Blank wall}, Blind wall, etc. See under {Blank}, {Blind},
      etc.
   {To drive to the wall}, to bring to extremities; to push to
      extremes; to get the advantage of, or mastery over.
   {To go to the wall}, to be hard pressed or driven; to be the
      weaker party; to be pushed to extremes.
   {To take the wall}. to take the inner side of a walk, that
      is, the side next the wall; hence, to take the precedence.
      ``I will take the wall of any man or maid of Montague's.''
      --Shak.
   {Wall barley} (Bot.), a kind of grass ({Hordeum murinum})
      much resembling barley; squirrel grass. See under
      {Squirrel}.
   {Wall box}. (Mach.) See {Wall frame}, below.
   {Wall creeper} (Zo["o]l.), a small bright-colored bird
      ({Tichodroma muraria}) native of Asia and Southern Europe.
      It climbs about over old walls and cliffs in search of
      insects and spiders. Its body is ash-gray above, the wing
      coverts are carmine-red, the primary quills are mostly red
      at the base and black distally, some of them with white
      spots, and the tail is blackish. Called also {spider
      catcher}.
   {Wall cress} (Bot.), a name given to several low cruciferous
      herbs, especially to the mouse-ear cress. See under
      {Mouse-ear}.
   {Wall frame} (Mach.), a frame set in a wall to receive a
      pillow block or bearing for a shaft passing through the
      wall; -- called also {wall box}.
   {Wall fruit}, fruit borne by trees trained against a wall.
   {Wall gecko} (Zo["o]l.), any one of several species of Old
      World geckos which live in or about buildings and run over
      the vertical surfaces of walls, to which they cling by
      means of suckers on the feet.
   {Wall lizard} (Zo["o]l.), a common European lizard ({Lacerta
      muralis}) which frequents houses, and lives in the chinks
      and crevices of walls; -- called also {wall newt}.
   {Wall louse}, a wood louse.
   {Wall moss} (Bot.), any species of moss growing on walls.
   {Wall newt} (Zo["o]l.), the wall lizard. --Shak.
   {Wall paper}, paper for covering the walls of rooms; paper
      hangings.
   {Wall pellitory} (Bot.), a European plant ({Parictaria
      officinalis}) growing on old walls, and formerly esteemed
      medicinal.
   {Wall pennywort} (Bot.), a plant ({Cotyledon Umbilicus})
      having rounded fleshy leaves. It is found on walls in
      Western Europe.
   {Wall pepper} (Bot.), a low mosslike plant ({Sedum acre})
      with small fleshy leaves having a pungent taste and
      bearing yellow flowers. It is common on walls and rocks in
      Europe, and is sometimes seen in America.
   {Wall pie} (Bot.), a kind of fern; wall rue.
   {Wall piece}, a gun planted on a wall. --H. L. Scott.
   {Wall plate} (Arch.), a piece of timber placed horizontally
      upon a wall, and supporting posts, joists, and the like.
      See Illust. of {Roof}.
   {Wall rock}, granular limestone used in building walls. [U.
      S.] --Bartlett.
   {Wall rue} (Bot.), a species of small fern ({Asplenium
      Ruta-muraria}) growing on walls, rocks, and the like.
   {Wall spring}, a spring of water issuing from stratified
      rocks.
   {Wall tent}, a tent with upright cloth sides corresponding to
      the walls of a house.
   {Wall wasp} (Zo["o]l.), a common European solitary wasp
      ({Odynerus parietus}) which makes its nest in the crevices
      of walls.
   

3. \Wall\, v. t. [imp. & p. p. {Walled}; p. pr. & vb. n.
   {Walling}.]
   1. To inclose with a wall, or as with a wall. ``Seven walled
      towns of strength.'' --Shak.
            The king of Thebes, Amphion, That with his singing
            walled that city.                     --Chaucer.
   2. To defend by walls, or as if by walls; to fortify.
            The terror of his name that walls us in. --Denham.
   3. To close or fill with a wall, as a doorway.
   

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[Jargon File]

Cities were surrounded by walls, as distinguished from "unwalled villages" (Ezek. 38:11; Lev. 25:29-34). They were made thick and strong (Num. 13:28; Deut. 3:5). Among the Jews walls were built of stone, some of those in the temple being of great size (1 Kings 6:7; 7:9-12; 20:30; Mark 13:1, 2). The term is used metaphorically of security and safety (Isa. 26:1; 60:18; Rev. 21:12-20). (See FENCE.)