Verb
1. make sharp or sharper;
"sharpen the knives"2. make sharp or sharper;
"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"