A block of stone used for sharpening the blade of a knife, chisel, axe, or sword. You rub the blade along the stone at a steady angle and it takes off a very thin layer of metal, leaving a fine edge. Many kinds are used wet, with water or oil on the surface to carry away the metal dust — Japanese kitchen knives are famously sharpened this way, and chefs, woodworkers, and gardeners all keep one.

A block of stone一塊石頭 used for sharpening用來磨 the blade of a knife, chisel, axe, or sword刀子、鑿子、斧頭或劍的刀刃. You你 rub the blade沿著石頭 along the stone把刀刃磨過去 at a steady angle以穩定的角度, and it takes off磨掉 a very thin layer of metal非常薄的一層金屬, leaving留下 a fine edge銳利的刀口. Many kinds很多種 are used wet是濕著用的, with water or oil表面上有水或油 on the surface to carry away the metal dust把金屬粉屑帶走 — Japanese kitchen knives日本廚刀 are famously sharpened this way著名地就是這樣磨的, and chefs, woodworkers, and gardeners廚師、木工、園丁 all keep one都會備一塊.

It is a plain, ordinary noun; nothing formal about it.

It它 is a plain, ordinary noun是一個平常、普通的名詞; nothing formal about it一點都不正式.

English also uses it as a picture: something that sharpens a person or an idea rather than a blade — "hardship was the whetstone of his talent", "a good rival is a whetstone for the mind". That figurative use is the one you meet most often in reading, and it always carries the same feeling: the friction is unpleasant, but the result is a keener edge.

English英文 also uses it as a picture也把它當作一種比喻: something有某樣東西 that sharpens能磨利 a person or an idea rather than a blade一個人或一個想法,而不是刀刃 — "hardship was the whetstone of his talent""苦難是他才能的磨刀石", "a good rival is a whetstone for the mind""一個好對手是心智的磨刀石". That figurative use那個比喻用法 is the one就是 you meet most often你最常遇到的 in reading在閱讀裡, and it always carries而且它總是帶著 the same feeling同樣的感覺: the friction摩擦 is unpleasant是不舒服的, but the result但結果 is a keener edge是更銳利的刀口.