Peephole (noun)

1. A small hole in a door or wall that allows someone to see who is outside without opening the door or wall.
2. An opening or aperture in a surface that allows one to see through it.

Origin:

The word "peephole" is a noun that refers to a small hole in a door or wall that allows someone to see who is outside without opening the door or wall. it is likely derived from the verb "to peep" which is of old english origin. .

Examples:

1. She used the peephole to see who was knocking at the door.
2. He installed a peephole in his front door for added security.
3. The peephole provided a limited view of the outside.
4. The peephole had a small cover to protect it from dirt.
5. He looked through the peephole to see who was on the other side of the door.