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