peephole

/ˈpiːphoʊl/
noun
  1. A small opening in a door or wall that you look through to see who is on the other side.
    • The hotel room door had a peephole so guests could see who was knocking.
    • He installed a peephole in the front door for extra security.
    • She checked the peephole before opening the door to the delivery person.
  2. A small hole or opening used for looking into something, such as a device or a hidden area.
    • The telescope had a tiny peephole for viewing distant stars.
    • Children pressed their eyes to the peephole in the fence to watch the game.
    • The security camera was hidden behind a peephole in the wall.
Synonyms
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