Definitions

1. noun

a stone wheel used for grinding or sharpening tools or other objects, typically turned by hand or by a foot-powered or animal-powered machine.

“The blacksmith used a grindstone to sharpen his tools.”

2. noun

something that is very tiring or wearsome, especially a repetitive task.

“The daily commute was a grindstone, but he had to do it to support his family.”

3. verb

to wear down or smooth something, especially by turning it against a surface.

“The sandpaper will grindstone the rough edge of the wood.”