3. n. (aviation) The highest altitude at which an aircraft can safely maintain flight.
4. n. (meteorology) 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.".
Even though it was cloudy, there was still enough ceiling for the Blue Angels to perform a great show.
5. n. (mathematics) 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
