Definition of "Sharpen" :

verb: put (an image) into focus

verb: become sharp or sharper

"The debate sharpened."

verb: make crisp or more crisp and precise

"We had to sharpen our arguments."

verb: make (one's senses) more acute

"This drug will sharpen your vision."

verb: give a point to

verb: raise the pitch of (musical notes)

verb: make sharp or sharper

"Sharpen the knives."

verb: make (images or sounds) sharp or sharper