1. a hinged or removable door in a floor, ceiling, or roof
2. a concealed entrance or exit, especially one used for escape or surprise

Examples

• The old house had a trapdoor leading to the basement.
• She lifted the trapdoor in the attic floor to access the storage space.
• The magician disappeared through a trapdoor on the stage.
• Pirates used a trapdoor to hide their treasure below deck.
• The spider waited beneath its trapdoor for unsuspecting prey.
• Workers installed a trapdoor in the roof for emergency access.
• The secret passage was hidden behind a cleverly disguised trapdoor.