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
"The physicist adjusted the grating on the spectrometer to separate the starlight into its constituent colors for analysis."
A barrier that has parallel or crossed bars blocking a passage but admitting air.
"The cat poked its head through the metal grating in the basement door to sniff at the leftovers on the floor."
present participle of grate
"The sound of the cheese being grated on the metal board was incredibly grating to my ears."
Harsh and unpleasant.
"The constant sound of his fingernails on the chalkboard was absolutely grating to my ears."