Focus on the pronunciation of shelf
English definition of “shelf”
/ʃelf/ /ʃelvz/ noun [C] (plural shelves)
› a long flat board fixed horizontally, for example against a wall or inside a cupboard, on which objects are stored or shown for sale: In another room, stacked on every available shelf are four to five hundred large storage boxes. Supermarket shelves are filled with cheap, mass-produced food that is packed with calories. fill/refill the shelves stock/restock the shelves The manufacturer has asked retailers to remove the product from the shelves.
off the shelf › COMMERCE, MARKETING if a product can be bought off the shelf, it does not need to be specially made or requested: It's often cheaper if you buy wallpaper off the shelf, rather than having to order it. The electronic components needed to make the sensors were easily available off the shelf.