Ceiling \Ceil"ing\, n. [See {Cell}, v. t.] 1. (Arch.) (a) The inside lining of a room overhead; the under side of the floor above; the upper surface opposite to the floor. (b) The lining or finishing of any wall or other surface, with plaster, thin boards, etc.; also, the work when done. 2. (Naut.) The inner planking of a vessel. {Camp ceiling}. See under {Camp}. {Ceiling boards}, Thin narrow boards used to ceil with.