Shelf (noun)

1. A flat surface, typically in a kitchen or bathroom, that projects from a wall or partition and is used to hold objects.
2. A projecting flat surface on a rock, mountain, or underwater formation.
3. A flat surface on a piece of furniture, such as a bookcase, that is used to hold objects.

Origin:

Old english scelf "shelf, ledge", of germanic origin; related to dutch schelf and german scholle "shelf".

Examples:

1. The books were on the shelf.
2. He placed the vase on the shelf.
3. The shelf held several jars of preserves.
4. The shelf was made of wood.
5. Shelf life of the product is limited.