grating
 光柵,摩擦,摩擦聲(a.)刺耳的
 grat·ing /ˈgretɪŋ/ 名詞
 光柵,柵欄,格子,格柵,線柵
 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.
 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 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.
 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.
 Grat·ing, a.  That grates; making a harsh sound; harsh. -- Grat*ing*ly, adv.
 Grat·ing, n. A harsh sound caused by attrition.
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 grating
      adj : unpleasantly harsh or grating in sound; "a gravelly voice"
            [syn: gravel, gravelly, rasping, raspy, rough]
      n 1: a barrier that has parallel or crossed bars blocking a
           passage but admitting air [syn: grate]
      2: a frame of iron bars to hold a fire [syn: grate]
      3: optical device consisting of a surface with many parallel
         grooves in it; disperses a beam of light (or other
         electromagnetic radiation) into its wavelengths to produce
         its spectrum [syn: diffraction grating]