Grat″ing (?), n. 1. A partition, covering, or frame of parallel or cross bars; a latticework resembling a window grate; as, the grating of a prison or convent.
2. (Optics) A system of close equidistant and parallel lines lines or bars, especially lines ruled on a polished surface, used for producing spectra by diffraction; — called also diffraction grating.
3. pl.(Naut.) The strong wooden lattice used to cover a hatch, admitting light and air; also, a movable Lattice used for the flooring of boats.