trapdoor

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

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

Computing, Engineering, Mathematics, Natural sciences, Physical sciences, Sciences A secret method of obtaining access to a program or online system; a backdoor.

Computing, Cryptography, Engineering, Mathematics, Natural sciences, Physical sciences, Sciences The special information that permits the inverse of a trapdoor function to be easily computed.

Business, Mining A door in a level for regulating the ventilating current; a weather door.