[{"Bold_text": "noun", "List Items": ["a fixed frame of bars or the like covering an opening to exclude persons, animals, coarse material, or objects while admitting light, air, or fine material.", "Physics. diffraction grating diffraction grating."]}, {"Bold_text": "adjective", "List Items": ["irritating or unpleasant to one's feelings.", "(of a sound or noise) harsh, discordant, or rasping."]}]