1 : to reduce to powder or pieces by friction (as in a mill or with the teeth)2 : to wear down, polish, or sharpen by friction : WHET3 : to press with a scraping noise : GRIT4 : OPPRESS 2, harass5 a : to operate or produce by turning a crank b : to produce by steady hard work <grind out an essay>6 : to move with difficulty or friction especially so as to make a scraping noise <grind the gears>