The Collaborative International Dictionary of English v.0.48:

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.
          [1913 Webster]

   2. (Naut.) The inner planking of a vessel.
      [1913 Webster]

   Camp ceiling. See under Camp.

   Ceiling boards, Thin narrow boards used to ceil with.
      [1913 Webster]