2.NounAn object used to erase or remove something written or drawn by a pen or a pencil.
"I have worn out the eraser on this pencil."
3.NounAn object used to erase something written either by chalk on a chalkboard, by a marker on a whiteboard, or by some other erasable implement; a chalkboard eraser, whiteboard eraser, etc.
4.NounAn overwriter program used to prevent data recovery.