Read the dictionary definition of sharpen. All definitions for this word.
1. put (an image) into focus
1. Please focus the image; we cannot enjoy the movie
2. become sharp or sharper
1. The debate sharpened
3. make crisp or more crisp and precise
1. We had to sharpen our arguments
4. make (one's senses) more acute
1. This drug will sharpen your vision
5. give a point to
1. The candles are tapered
6. raise the pitch of (musical notes)
7. make sharp or sharper
1. sharpen the knives
8. make (images or sounds) sharp or sharper