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Physical Security & Locksmithing Glossary

Key terminology and technical concepts referenced throughout the wiki.

A​

  • Astragal: A vertical molding or plate attached to the meeting edge of a door to cover the gap and protect latch hardware from external tampering.
  • Auxiliary Deadlatch Pin: A secondary small pin alongside a latch bolt that, when depressed by the strike plate, prevents the main latch from being depressed or slipped.

B​

  • Bitting: The specific pattern of depth cuts on a key blade designed to set pins or wafers to the correct heights.
  • Bottom of Keyway (BOK): Applying rotational tension by placing the wrench at the bottom (pin side) of the keyway.

C​

  • Core (Plug): The inner rotating portion of a lock cylinder that turns to activate the locking cam or tailpiece.
  • Crash Bar: A horizontal egress device that unlatches a door when push pressure is applied.

F​

  • Fail-Safe: An electric lock that unlocks automatically when electrical power is interrupted (e.g., standard magnetic locks).
  • Fail-Secure: An electric lock that remains mechanically locked when electrical power is lost (e.g., standard electric strikes).
  • False Set: A slight rotation of the plug that occurs when a spool or security pin catches on its narrow waist rather than fully setting.

R​

  • Request to Exit (REX): A sensor (PIR, motion, or switch) designed to detect an occupant approaching an exit and signal the electronic access system to unlock the door.

S​

  • Shear Line: The circular boundary plane between the rotating plug and the stationary cylinder housing.
  • Single Pin Picking (SPP): The method of lifting each pin individually to the shear line while feeling for binding order.

T​

  • Top of Keyway (TOK): Placing a flat tension prybar at the top of the keyway to maximize pick mobility.