wall

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun An upright structure of masonry, wood, plaster, or other building material serving to enclose, divide, or protect an area, especially a vertical construction forming an inner partition or exterior siding of a building.
• noun A continuous structure of masonry or other material forming a rampart and built for defensive purposes.
• noun A structure of stonework, cement, or other material built to retain a flow of water.
• noun Something resembling a wall in appearance, function, or construction, as the exterior surface of a body organ or part.
• noun Something resembling a wall in impenetrability or strength.
• noun An extreme or desperate condition or position, such as defeat or ruin.
• noun Sports The vertical surface of an ocean wave in surfing.
• transitive verb To enclose, surround, or fortify with or as if with a wall: synonym: enclose.
• transitive verb To divide or separate with or as if with a wall. Often used with off:
• transitive verb To confine or seal behind a wall; immure.
• transitive verb To block or close (an opening or passage, for example) with or as if with a wall.
• idiom (off the wall) Extremely unconventional.
• idiom (off the wall) Without foundation; ridiculous.
• idiom (up the wall) Into a state of extreme frustration, anger, or distress.
• idiom (writing/handwriting) An ominous indication of the course of future events.

from The Century Dictionary.

• To boil.
• To well, as water; spring.
• To inclose with a wall or as with a wall; furnish with walls: as, to wall a city.
• To defend by walls; fortify.
• To obstruct or hinder as by a wall.
• To fill up with a wall.
• In English university slang, same as gate.
• noun A spring of water.
• noun Abbreviations of Wallachian.
• noun A disease of the eyes: same as walleye.
• noun A work or structure of stone, brick, or other materials, serving to inclose a space, form a division, support, superincumbent weight, or afford a defense, shelter, or security.
• noun A solid and permanent inclosing fence of masonry, as around a field, a garden, a park, or a town.
• noun A rampart; a fortified enceinte or barrier: often in the plural. See cuts under chemm-deronde, fortification, and retaining wall.
• noun Something which resembles or suggests a wall: as, a wall of armed men; a wall of fire.
• noun A defense; means of security or protection.
• noun In mining, one of the surfaces of rock between which the vein or lode is inclosed; the country, or country rock, adjacent to the vein. See vein.
• noun In heraldry, a bearing having some resemblance to a wall, usually embattled.
• noun In anatomy and zoology, a paries; an extended investing or containing structure or part of the body: as, a cell-wall; the walls of the chest or abdomen: generally in the plural
• noun In cor als, the proper outer investment of the visceral chamber, whether of a single corallum or of a single corallite of a compound corallum.
• noun Same as wall-knot

from the GNU version of the Collaborative International Dictionary of English.

• transitive verb To inclose with a wall, or as with a wall.
• transitive verb To defend by walls, or as if by walls; to fortify.
• transitive verb To close or fill with a wall, as a doorway.
• noun (Naut.) A kind of knot often used at the end of a rope; a wall knot; a wale.
• noun 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.
• noun 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.
• noun A defense; a rampart; a means of protection; in the plural, fortifications, in general; works for defense.
• noun An inclosing part of a receptacle or vessel.
• noun The side of a level or drift.
• noun The country rock bounding a vein laterally.
• noun Blind wall, etc. See under Blank, Blind, etc.
• noun to bring to extremities; to push to extremes; to get the advantage of, or mastery over.
• noun to be hard pressed or driven; to be the weaker party; to be pushed to extremes.