Definitions
1.nounA hinged or sliding door set into a floor or ceiling.
2.nounSuch a trap set into the floor of a stage to allow fast exits and entrances.
3.nounA secret method of obtaining access to a program or online system; a backdoor.
4.nounThe special information that permits the inverse of a trapdoor function to be easily computed.
5.nounA door in a level for regulating the ventilating current; weather door.