SHARPEN (5 letters) The term 'make keener' can be broken down into two crossword solutions: HONE (4 letters) and SHARPEN (5 letters). HONE is a verb meaning to make something sharper or more precise, while SHARPEN is a verb meaning to make something sharper or more pointed. Both words are used to describe the process of making something more acute or intense. In this context, the term 'make keener' implies that something is being made more precise or intense.