a surface with many parallel grooves in it; disperses a beam of light (or other electromagnetic radiation) into its wavelengths to produce its spectrum
a frame of iron bars to hold a fire
a barrier that has parallel or crossed bars blocking a passage but admitting air
unpleasantly harsh or grating in sound; "a gravelly voice"
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
