a revolving stone shaped like a disk; used to grind or sharpen or polish edge tools
A flat, circular stone, revolving on an axle, for grinding or sharpening tools, or shaping or smoothing objects
A grindstone is a large round stone that turns like a wheel and is used for sharpening knives and tools. a large round stone that turns like a wheel, and is used for making tools and knives sharp when they are rubbed against it keep your nose to the grindstone nose (11)