Ceil

1. To line or finish (a surface, such as a wall), with plaster, stucco, thin boards, or similar.
2. To set a higher bound.

noun

A ceiling

1. The overhead closure of a room.

   the dining room had an ornate ceiling

2. The upper limit of an object or action.
3. The highest altitude at which an aircraft can safely maintain flight.
4. The measurement of visible distance from ground or sea level to an overcast cloud cover; under a clear sky, the ceiling measurement is identified as "unlimited."
5. The smallest integer greater than or equal to a given number.

   the ceiling of 4.5 is 5, the ceiling of -4.5 is -4

6. The inner planking of a vessel.