What does "shelf" mean?

Shelf: A sand bank in the sea, or a rock, or ledge of rocks, rendering the water shallow, and dangerous to ships. On the tawny sands and shelves. Milton. On the secret shelves with fury cast. Dryden.

Additional senses

  1. 2.(Mining) A stratum lying in a very even manner; a flat, projecting layer of rock.
  2. 3.(Naut.) A piece of timber running the whole length of a vessel inside the timberheads. D. Kemp. To lay on the shelf, to lay aside as unnecessary or useless; to dismiss; to discard.

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