day gate
n. a barrier used to restrict passage during normal business hours, normally used at a vault entrance
day key
n. 1. the key for a day gate or day operation of a safe or vault lock 2. a cash register key which does not allow audit or reset functions 3. see 'change key'
1. n. a locking device, other than the primary lock, used to maintain the safe in a locked condition, 2. v. to insecurely close a safe or vault door without scrambling the combination, even though the door may not be opened by simply turning or pulling the handle
dead pin
n. an immovable pin in a tubular lock which functions as a ward
n. a bolt, which requires a deliberate action to extend, and which resists end pressure in the unlocking direction when fully extended
n. a lock which incorporates a deadbolt
adj. pertaining to any feature which, when fully engaged, resists attempts to move the latch or bolt in the unlocking direction through direct pressure
deadlocking latch
n. a latchbolt with a deadlocking mechanism
declining step key
n. a key whose cuts are equal or deeper as you proceed from bow to tip
deco key finish
n. any design embossed or imprinted on a key to give it an aesthetic appearance 
v. to determine a key combination by physical measurement of a key and/or cylinder parts
decoder gauge
n. a measuring device which helps determine the combination of a lock or cylinder without removing the tumblers
deflector cover
n. a removable shield designed to prevent pin point drilling on a safe
degree of rotation
n. a specification for the angle at which a cut is made into a key blade as referenced from the perpendicular; e.g., right (R or 2), left (L or 1) or center (= perpendicular) (C). This specification is typically used for some high security keys.
v. the process on older laminated door safes of having to remove some layers of the lamination to allow access to the lock
delayed action timer
n. a secondary device which prevents movement of a bolt or boltworks until a set amount of time has elapsed. The device is normally set or activated as part of the unlocking process.
delayed egress
n. an exit that will not open until a preset amount of time after actuation has elapsed
department master key
n. a master key which operates all or most master keyed locks of a given department
depth key set
n. a set of keys used to make a code original key on a key duplicating machine to a lock manufacturer's given set of key bitting specifications. Each key is cut with the correct spacing to one depth only in all bitting positions, with one key for each depth.
derived series
n. a series of blind codes and bittings which are directly related to those of another bitting list
detector lever
n. a lever tumbler with an extra gate that, when elevated beyond the bolt fence, accepts a latching fence to prevent further movement of the tumbler
detector lock
n. a lock that incorporates a detector lever in its mechanism
detention lock
n. a lock designed for securing a cell or other area in a prison or jail
abb. Door and Hardware Institute
1. n. the typically rotatable member of a combination lock that may be used to differentiate locations on the combination wheels and cause operation of the lock, 2. v. the act of turning or rotating a dial
dial insert lock
n. a key operated cylinder used to lock the dial on a combination lock
dial ring
n. an escutcheon for a combination lock dial
n. 1. a device, which automatically places a telephone call to a pre-set number when, activated 2. an electro-mechanical device which systematically tries different combinations on a dial operated combination lock
diamond back
adj. pertaining to a rim cabinet lock whose mounting flanges and case forms the general shape of a diamond
diamond pick
n. a tumbler manipulation device with a triangular protrusion at its tip
digital dial
n. a rotatable dial that causes a separate readable index, (typically digital), to change
digital dialer
n. a telephone communication device that dials a programmed telephone number, and transmits, via tones or pulses, one or more signals to a digital receiver
n. a key cut in a dimple key
dimple key
n. a key whose cuts are drilled or milled into its blade surfaces. The cuts normally do not change the blade silhouette.
direct code
n. a designation assigned to a particular key which includes the actual combination of the key
direct drive
adj. of or pertaining to a combination lock with the drive cam mounted on the dial's spindle shaft
direction of rotation
n. the direction a combination lock dial is to be turned when the combination is worked. It usually is specified as clockwise (CW) or right (R), or counter clockwise (CCW) or left (L).
disc tumbler
n. 1. a flat tumbler which must be drawn into the cylinder plug by the proper key so that none of its extremities extends into the shell 2. a flat, usually rectangular tumbler with a gate which must be aligned with a sidebar by the proper key
diskette lock
n. a usually key operated device which blocks access to the drive for a removable disk
display key
n. a special change key in a hotel master key system which will allow access to one designated guest room, even if the lock is in the shut out mode. It may also act as a shut out key for that room.
divided plug keyway
n. a cylinder plug divided at the keyway into two parts. Either part may be replaced to result in a different keyway combination via different warding for the keyway
1. v. to place an exit device in the holdback mode 2. n. in marine applications the latch for a hatch
dogging cylinder
n. a key operated cylinder used to dog an exit device
dogging device
n. in an exit device, a mechanism used to temporarily disable the latch from locking
dogging key
n. a key or tool used to dog an exit device
dogging screw
n. a screw used to dog an exit device
door bumper
n. an obstruction installed to prevent a door or lock from contacting another object
door closer
n. a device designed to regulate the closing of a door automatically by various means
door control
n. any device which controls the opening, closing or position of a door
door holder
n. any device designed to maintain a door in the open position
door lug
n. a non-movable projection on a safe door that helps keep the door in the locked position
door puller
n. a tool designed to open a safe deposit box by forcibly pulling the door and breaking the lock
door silencer
n. a bumper installed in the jamb stop to quiet the closing of a door
door swing
adj. the direction and degree to which a door opens, as LH 90, RH 180, etc.
door viewer
n. a device with one or more lenses, mounted in a door at eye level, which allows a limited view through a door
double-acting closer
n. a door closer designed to be used on a double-acting door
double- acting door
adj. a door that may be pushed open from either side
double-acting hinge
n. a hinge which permits movement of a door in either direction from the closed position
double-acting lever tumbler
n. one that must be lifted a precise amount, neither too little nor too much to allow movement of a bolt
double bitted key
n. a key typically bitted on two opposite surfaces
double cut
1. n. two bittings for the same tumbler position 2. adj. see "double bitted key"
double cylinder
adj. pertaining to a lock with two keyed cylinders
double cylinder deadlock
n. a deadbolt lock whose bolt may be operated by a key from either side
n . a shape consisting of two opposing arcs and two opposing flats adj. 2. Having such a shape.
double-D punch
n. a tool used to make a double-D hole
double horn
adj. of or pertaining to a safe deposit type lock which requires two separate holes through the door
double locking
adj. of or pertaining to a lock with one or more bolts with different functions, typically a latch and a deadbolt
double pin
v. o place more than one master pin in a single pin chamber
double throw bolt
n. a deadbolt that has two distinct extended positions, both of which are deadlocked
drawback latch/lock
n. a latch/lock whose latch is disengaged by pushing or pulling an actuator toward the hinge side of the jamb
draw sheet
n. a page with a completed matrix of potential combinations used in Matrix Format Master Keying
drill point
n. the exact measurement of the location used to drill a locked up container to effect an opening
drive cam
n. the first wheel rotated by a dial or key that has an opening designed to allow the fence, lever, or tailbar to enter and facilitate in opening of the lock or safe
adj. pertaining to a latch or bolt with a round face
driver spring
n. a spring placed on top of the pin stack to exert pressure on the pin tumblers
n. a pivoting or swinging dust cover, see also "increment"
drop bolt
n. a lock with an interlocking bolt which moves vertically and may enter loops on the strike
drop in
n. the gate area of the drive cam where the lever nose drops into. Usually identified with a corresponding number on the dial
drop-in point
n. the location in a combination lock where the wheel gates are aligned with the fence
drop ring
n. a looped handle which can pivot, typically recessed and falls flush with the door face when not in use
dual custody
n. 1. a function designed to require the presence of two persons with two different keys, combinations or codes to operate the same device 2. adj. Pertaining to such a function
dual locking cylinder
n. a style of lock cylinder whose key operates two independent locking mechanisms within the cylinder
dumbbell pin
n. a spool pin with serrations at the larger diameter ends
dumb card
n. an authorization credential that presents recorded data only
dumb reader
n. an access control interrogation device that can only relay data to a controller
adj. pertaining to any type of non-active device applied for aesthetic purposes
dummy cylinder
n. a non-functional facsimile of a rim or mortise cylinder used for appearance only, usually to conceal a cylinder hole
dummy trim
n. non-active trim applied for aesthetic purposes
n. an early trade name used by Yale for locks which offer the functionality of master keying by incorporating two cylinders on the same side of the door, or two keyways in a lever tumbler lock. One keyway is for the change key and the other keyway is for the 'master key'.
v. to copy, see also "duplicate key"
duplicate key
n. any key reproduced from a pattern key
duress code
n. a special combination or operation sequence which conveys an alarm or other signal to a remote location while allowing access
dust box
n. an enclosure applied under a strike to enhance appearance and/or performance
dust cover
n. a device designed to prevent foreign matter from entering a mechanism through the keyway
dustproof cylinder
n. a cylinder designed to prevent foreign matter from entering either end of the keyway
dust proof strike
n. a typically floor mounted strike that has a spring loaded internal plunger designed to keep the receptacle free of dust and debris
Dutch door bolt
n. a bolt which secures the top section of a Dutch door to the bottom section


A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Appendix

This listing of the Locksmith Dictionary is courtesy of