A small hole, opening, or piece of glass, especially in a door, through which one can look without being seen.
A series of holes punched through something in order to assist in separating parts.
That portion of a surface that remains after an open disk is removed from it.
An abnormal opening in an organ, such as a rupture.
Any opening in a solid object.
The act of perforating or the state of being perforated.