sharpen

verb

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