The Collaborative International Dictionary of English v.0.48:

Shelf \Shelf\, n.; pl. Shelves. [OE. shelfe, schelfe, AS.
   scylfe; akin to G. schelfe, Icel. skj[=a]lf. In senses 2 & 3,
   perhaps a different word (cf. Shelve, v. i.).]
   1. (Arch.) A flat tablet or ledge of any material set
      horizontally at a distance from the floor, to hold objects
      of use or ornament.
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   2. A sand bank in the sea, or a rock, or ledge of rocks,
      rendering the water shallow, and dangerous to ships.
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            On the tawny sands and shelves.       --Milton.
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            On the secret shelves with fury cast. --Dryden.
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   3. (Mining) A stratum lying in a very even manner; a flat,
      projecting layer of rock.
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   4. (Naut.) A piece of timber running the whole length of a
      vessel inside the timberheads. --D. Kemp.
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   To lay on the shelf, to lay aside as unnecessary or
      useless; to dismiss; to discard.
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