A grindstone is a big heavy wheel made of stone. You turn it, and you hold a tool or a knife against it so the rough stone rubs the metal and makes a new sharp edge.

A grindstoneGrindstone（磨刀石） is a big heavy wheel made of stone是一個用石頭做的又大又重的輪子。You turn it你轉動它，and you hold a tool or a knife against it把工具或刀子貼著它，so the rough stone rubs the metal讓粗糙的石面摩擦金屬，and makes a new sharp edge磨出新的鋒利刀刃。

Smiths, farmers, and kitchen workers used one for centuries; you may still see a small one in an old workshop. It is a concrete thing, not a fancy word.

Smiths, farmers, and kitchen workers鐵匠、農夫，和廚房工作者 used one for centuries用了它好幾百年；you may still see a small one in an old workshop在老工坊裡你可能還會看到一個小的。It is a concrete thing它是個實實在在的東西，not a fancy word不是什麼花俏的字。

People also keep the picture in an idiom: if you keep your nose to the grindstone, you work hard and do not look up, as if your face were close to that spinning stone. That does not mean the grindstone itself is “hard work”; the stone is still the stone.

People also keep the picture in an idiom大家也把這個畫面留在一句成語裡：if you keep your nose to the grindstone如果你keep your nose to the grindstone（把鼻子貼在磨刀石上），you work hard and do not look up意思是你努力工作、不抬頭休息，as if your face were close to that spinning stone就好像你的臉一直貼近那顆轉動的石頭一樣。That does not mean the grindstone itself is "hard work"這不代表grindstone這個字本身就是「辛苦工作」的意思；the stone is still the stone那顆石頭終究還是那顆石頭。

You grind on a grindstone; you do not “grindstone” something as a verb in ordinary talk.

You grind on a grindstone你是在grindstone上grind（磨東西）；you do not "grindstone" something as a verb in ordinary talk平常講話不會把grindstone直接當動詞用。