n.1 a the upper interior surface of a room or other similar compartment. b the material forming this.
2 an upper limit on prices, wages, performance, etc.
3 Aeron. the maximum altitude a given aircraft can reach.
4 Naut. the inside planking of a ship's bottom and sides.
Etymology: ME celynge, siling, perh. ult. f. L caelum heaven or celare hide