shelf

Từ điển American Heritage Dictionary 4th

shelf (shĕlf)n. pl. shelves (shĕlvz)
1.
a. 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.
b. The contents or capacity of such a structure.
c. Something, such as a projecting ledge of rock or a balcony, that resembles such a structure.
2. A reef, sandbar, or shoal.
3. Bedrock.Idioms:off the shelf
From ready-made merchandise in stock:
supplies that were available off the shelf.on the shelf
1. In a state of disuse.
2.
a. Unemployed.
b. Out of circulation.
c. Retired. [Middle English, probably from Middle Low German schelf. See skel-¹ in Indo-European Roots.] shelfʹful' n.