shelf

Concise Oxford English Dictionary © 2008 Oxford University Press:
shelf1

▶noun (pl. shelves)

• 1 a flat length of wood or rigid material attached to a wall or forming part of a piece of furniture, providing a surface for the storage or display of objects.

• 2 a ledge of rock or protruding strip of land.

  ■ a submarine bank, or a part of the continental shelf.

– phrases
off the shelf not designed or made to order.
on the shelf

• 1 no longer useful or desirable.

• 2 past an age when one might expect to be married.

– derivatives
shelf-ful noun (pl. shelf-fuls),
shelf-like adjective.

– origin ME: from Mid. Low Ger. schelf; rel. to OE scylfe ‘partition’, scylf ‘crag’.

Concise Oxford English Dictionary © 2008 Oxford University Press:
shelf2 Austral./NZ informal

▶noun (pl. shelfs) an informer. ▶verb inform on.

– origin 1930s: prob. from the phr. on the shelf ‘out of the way’.