Grindstone \Grind"stone`\, n. A flat, circular stone, revolving on an axle, for grinding or sharpening tools, or shaping or smoothing objects. {To} {hold, pat, or bring} {one's nose to the grindstone}, to oppress one; to keep one in a condition of servitude. They might be ashamed, for lack of courage, to suffer the Laced[ae]monians to hold their noses to the grindstone. --Sir T. North.