To rub over the surface of (something) with a sharp or
   rough instrument; to rub over with something that roughens by removing
   portions of the surface; to grate harshly over; to abrade; to make
   even, or bring to a required condition or form, by moving the sharp
   edge of an instrument breadthwise over the surface with pressure,
   cutting away excesses and superfluous parts; to make smooth or clean;
   as, to scrape a bone with a knife; to scrape a metal plate to an even
   surface.