Me: you have to define an ERASER for your exam
Guy Friend: A synthetic material made up of processed rubber,used to erase pencil marks
Me: a tool, common stationery item, useful, made f rubber, but various materials, used to correct mistakes, it picks up pencil pigment from paper, used widely, availiable in various fancy shapes, colours and varieties as per the purpose:pen marks or kneaded erasers used for art..
(That is my definition)