砥ㄉㄧˇdǐ礪ㄌㄧˋlì

砥、礪都是磨刀石。砥礪引申為磨鍊。《淮南子·脩務》：「有時而脩，砥礪磨堅，莫見其損。」似磨鍊﹑琢磨

英whetstone, (fig.) to hone, to temper, to encourage