trapdoor

A hinged or sliding door in a floor, roof, or ceiling.

In mining, a door designed to direct air-currents in ventilating systems, or to prevent, surface wind from deranging the normal direction of air-currents.

A door in a floor or roof which when shut is flush, or nearly so, with what surrounds it.

A lifting or sliding door covering an opening in a roof or floor.

A door in a level for regulating the ventilating current; — called also weather door.

any one of several species of large spiders which make a nest consisting of a vertical hole in the earth, lined with a hinged lid, like a trapdoor. Most of the species belong to the genus Cteniza, as the California species (Cteniza Californica).

A hinged or sliding door set into a floor or ceiling.

Such a trap set into the floor of a stage to allow fast exits and entrances.

A secret method of obtaining access to a program or online system; a backdoor.

The special information that permits the inverse of a trapdoor function to be easily computed.