Gratings

noun

1. A barrier that has parallel or crossed bars blocking a passage but admitting air.
2. A frame of iron bars to hold a fire.
3. The loose material that comes from something being grated.

   "Add a few gratings of nutmeg to the hot milk."

4. An optical system of close equidistant and parallel lines or bars, especially lines ruled on a polished surface, used for producing spectra by diffraction.
5. (in the plural) The strong wooden lattice used to cover a hatch, admitting light and air; also, a movable lattice used for the flooring of boats.