To reduce to fragments, shreds, or powder by rubbing against an abrasive surface. To cause to make a harsh grinding or rasping sound through friction: grated her teeth in anger. To irritate or annoy persistently. Archaic To rub or wear away. To make a harsh rasping sound by or as if by scraping or grinding. To cause irritation or annoyance: a noise that grates on one's nerves. A harsh rasping sound made by scraping or rubbing: the grate of a key in a lock. A framework of parallel or latticed bars for blocking an opening. A framework of metal bars used to hold fuel or food in a stove, furnace, or fireplace. A fireplace. A perforated iron plate or screen for sieving and grading crushed ore. To equip with a grate.