1. Architecture/Construction:
- The upper interior surface of a room or other enclosed space. It is typically flat and horizontal, though there can be exceptions like vaulted or beamed ceilings.
- The maximum permissible height of a structure or part of a structure. This is often used in building codes or regulations.
2. Figurative/Metaphorical:
- A limit or maximum. For example: "There's a ceiling on how much I can spend."
- The highest attainable point. For example: "She reached the ceiling of her career."
3. Other:
- The upper surface of a cavity or compartment.
- A protective covering over an opening or area. This is often used for lighting fixtures or for hiding electrical wiring.
If you can provide more context about what you are looking for, I can give you a more precise definition of "ceiling".