grating

definition: unpleasantly harsh or grating in sound
example:
speech part: adjective
synonyms: rough
definition: optical device consisting of a surface with many parallel grooves in it
example:
speech part: noun
synonyms: diffraction grating
definition: a frame of iron bars to hold a fire
example:
speech part: noun
synonyms: grate
definition: a barrier that has parallel or crossed bars blocking a passage but admitting air
example:
speech part: noun
synonyms: grate

How grating is being used?