From The Collaborative International Dictionary of English v.0.48:
Grate \Grate\, v. t. [imp. & p. p. Grated; p. pr. & vb. n.
Grating.]
To furnish with grates; to protect with a grating or
crossbars; as, to grate a window.
[1913 Webster]
From The Collaborative International Dictionary of English v.0.48:
Grating \Grat"ing\, n. [See 2d Grate.]
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.
[1913 Webster]
2. (Optics) A system of close equidistant parallel lines or
bars, esp. lines ruled on a polished surface, used for
producing spectra by diffraction; -- called also
diffraction grating.
Note: Gratings have been made with over 40,000 such lines to
the inch, but those with a somewhat smaller number give
the best definition. They are used, e. g., to produce
monochromatic light for use in optical instruments such
as spectrophotometers.
[Webster 1913 Suppl.]
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.
[1913 Webster]
From The Collaborative International Dictionary of English v.0.48:
Grating \Grat"ing\, a. [See Grate to rub harshy.]
That grates; making a harsh sound; harsh. -- Grat"ing*ly,
adv.
[1913 Webster]
From The Collaborative International Dictionary of English v.0.48:
Grating \Grat"ing\, n.
A harsh sound caused by attrition.
[1913 Webster]