A trapdoor is a hinged or sliding door built into a floor, ceiling, or stage that opens to reveal a hidden space below or above. Picture a wooden panel in the floor of an old barn that lifts up to expose a ladder leading down to a cellar, or a square hatch in your attic floor that you push open to climb through.

Trapdoors serve practical purposes: they provide access to basements, crawl spaces, or storage areas without taking up wall space for a regular door. In theaters, stage crews use trapdoors for dramatic entrances and exits, making actors seem to appear or vanish mysteriously. Pirates and smugglers in adventure stories often hide treasure beneath trapdoors, and medieval castles sometimes had trapdoors that opened into dungeons.

The word captures something secretive about these doors. Unlike regular doors that everyone can see, a trapdoor might be covered by a rug or designed to blend in with the surrounding floor. You might not even know it's there until someone lifts it open. This hidden quality makes trapdoors fascinating in mysteries and exciting in escape rooms, where discovering a trapdoor might reveal a secret passage or hidden room.