shelf

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

• noun A flat, usually rectangular structure composed of a rigid material, such as wood, glass, or metal, fixed at right angles to a wall or other vertical surface and used to hold or store objects.
• noun The contents or capacity of such a structure.
• noun Something, such as a projecting ledge of rock or a balcony, that resembles such a structure.
• noun A reef, sandbar, or shoal.
• noun Bedrock.
• idiom (off the shelf) From ready-made merchandise in stock.
• idiom (on the shelf) In a state of disuse or inactivity.
• idiom (on the shelf) Out of consideration.

from The Century Dictionary.

• Same as shelve.
• noun A thin slab or plank, a piece of marble, slate, wood, or other material, generally long and narrow, fixed horizontally to a wall, and used for supporting small objects; in general, a narrow flat surface, horizontal or nearly so, and raised above a larger surface, as of a floor or the ground.
• noun In ship-building, an inner timber, or line of timbers, following the sheer of the vessel, and bolted to the inner side of ribs, to strengthen the frame and sustain the deck-beams. See cut under beam, 3.
• noun The charging-bed of a furnace.
• noun In scissors, the bottom of the countersink which receives the head of the screw uniting the two blades
• noun A rock, ledge of rocks, reef, or sand-bank in the sea, rendering the water shallow and dangerous to ships; a reef or shoal; a shallow spot.
• noun A projecting layer or ledge of rock on land.
• noun The bed-rock; the surface of the bed-rock; the rock first met with after removing or sinking through the superficial detritus.

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

• noun (Arch.) A flat tablet or ledge of any material set horizontally at a distance from the floor, to hold objects of use or ornament.
• noun A sand bank in the sea, or a rock, or ledge of rocks, rendering the water shallow, and dangerous to ships.
• noun (Mining) A stratum lying in a very even manner; a flat, projecting layer of rock.
• noun (Naut.) A piece of timber running the whole length of a vessel inside the timberheads.
• noun to lay aside as unnecessary or useless; to dismiss; to discard.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A flat, rigid, rectangular structure, fixed at right angles to a wall, and used to support, store or display objects.
• noun The capacity of such an object; as, a shelf of videos.
• noun A projecting ledge that resembles such an object.
• noun A reef, shoal or sandbar.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a projecting ridge on a mountain or submerged under water
• noun a support that consists of a horizontal surface for holding objects