A comprehensive glossary of terms, names and explanations of the locksmith trade.


Abus - High quality lock and security brand manufacture

Access Control - any barrier or device, either natural or man made, that limits or prohibits, free or unlimited access

Access Control Cylinder - a replacement for a mechanical cylinder which incorporates electronic access control and allows the original host lock to function without additional wiring or hardware modifications

Access Control Key Fob - any device other than a key designed to allow a token to be used and carried on a key ring

Active Leaf Door - the single door of a pair on which the active or locking hardware is mounted

Actuator - a device, usually connected to a cylinder, which, when activated, may cause a lock mechanism to operate

After Hours Depository - a secure locker or safe where items of value can be left out of hours

Alarm System - a system of electrical and/or electronic components which detect and report dangers, such as fire or intrusion

Anti Strike Plate - A device fitted on to the door or frame to stop the bolt or latch from being attacked.

Architectural Hardware - describes all fittings to a door, window or house. Such as - a letter box, house numbers, handles, door knobs, hinges etc

Attack Resistant - design qualities of a product that render brute force physical defeat methods less effective or ineffective

Automatic Closing - pertaining to a door which is equipped with a door closer, or other device to close it without manual intervention. Frequently found in Life Safety and fire code requirements.

Automatic deadbolt - a deadbolt designed to extend itself fully when the door is closed

Auxillary Lock - any lock installed in addition to the primary lock set


Back Plate - a thin piece of metal, usually with a concave portion, used with machine screws to fasten certain types of cylinders to a door

Back Check - the resistance provided by a door closer as a door is opened

Back Set - the distance between the centre of a cross-bore and the bolt edge of a door or drawer

Ball Catch - a latch which uses spring pressure to force a ball bearing into a recess in its strike

Barrel Bolt - a surface mounted slide bolt which has a cylindrical shape

Barrel Key - a type of bit key with a hole drilled into the shank from the tip

Bell Box (sounder box) - the protective enclosure for a bell or other alarm sounding device

Bicycle Padlock - a padlock with sufficient shackle clearance to secure a bicycle

Bike Lock - A lock designed especially for lock a bike. modern bike locks use tough metals that prevent hack sawing.

BI Fold Door - a door with two or more sets of hinges, the additional set(s) allows the door to have an accordion action when opened

Biometric Lock - of or pertaining to a lock with a hybrid mechanism, part of the mechanism identifies a physical attribute such as finger print, voice print, etc. while another part is a mechanical mechanism

Bit - the part of the key which serves as the blade, usually for use in a warded or lever tumbler lock

Bit Height - a measurement from the post of a bit key outward to the end of the bit

Bit Key - a key with one or more projecting bits

Bit Thickness - a measurement of the bit from one side to the other side

Bit Width - as inserted into a lock, a measurement from the leading edge to the trailing edge of a bit

Bitting Depth - the depth of a cut which is made into the blade of a key

Bitting Position - the location of a key cut

Blade - the portion of a key which may contain the cuts and/or millings

Blank - an uncut key

Body - the part of a lock assembly into which all the operating components are mounted, see also case

Bolt - any movable projection which blocks the movement of one object relative to another

Bow - the portion of the key which serves as a grip or handle

Bow Stop - a type of stop located near the key bow

Bow to Tip - a specification that a bitting combination is recorded starting at the bow and proceeding to the tip

Bullet Lock - a lock used mostly on shutters. Once the lock has been inserted into its housing it locks automatically. only unlocked with a key. Widely used in the UK on shop fronts.

Bump Key - a lock picking key with uniform steeples between cuts that is forced further into the lock via impact

Burglar Alarm - a system designed to detect and report conditions, which may indicate intrusion or attempted intrusion

Burglar Resistant - of or pertaining to a security container designed to resist forcible entry for a specified period of time determined by the rating of the container

Button Know - the knob in a key-in-knob lock that includes a push or turn button

Bypass Key - the key which operates a key override cylinder

Bypass Tool - a device that neutralizes the security of a locking device, or its application hardware, often taking advantage of a design weakness


Cam - a lock or cylinder component which transfers the rotational motion of a key or cylinder plug to the bolt works of a lock 2. the bolt of a cam lock

Cam Lock - a complete locking assembly in the form of a cylinder whose cam is the actual locking bolt

Card Access System - an access control system that utilizes a controlled security card as the credential

Card Holder - a person to whom a card has been issued

Card Reader - a device which interprets coding resident on or in cards

case - the housing or body of a lock

Case Cover - the portion of a lock case which is designed to be removable to allow access to the mechanism

Casement Window - a window with a sash which pivots or swings to open

Case Ward - any ward directly attached to or projecting from a lock case

Catch - any device that holds a door closed and may be released by simply pushing or pulling on the door

CCW - Counter Clockwise

Central Locking - a location designed for the express purpose of processing status signals for multiple alarm systems

Combination - the group of numbers which represent the bitting of a key and/or the tumblers of a lock or cylinder

Combination Lock - a lock which is operated by local input of a specific series or sequence of numbers or letters

Combination Wheel - a wheel type tumbler in a combination lock

Contact Point - the area on each side of the drive cam gate that the lever nose makes contact with. Most locks have a left contact point and a right contact point.

Contact Switch - electrical, magnetic or mechanical device that triggers a circuit(s) to open or closed depending on the application

contactless Smart Card - a card, conforming to the physical characteristics specified in ISO 7813 & 10536, which contains one or more integrated circuits and does not use contacts to obtain power and allow interface to external equipment

Cupboard Latch - a latching mechanism typically surface mounted to the outside of cabinet doors or drawers

Cut Edge - the part of the key blade which contains the cuts

Cut Key - a key which has been bitted or cut to fit a lock

Cylinder - a complete operating unit which usually consists of the plug shell, tumblers, springs, plug retainer, a cam/tailpiece or other actuating device, and all other necessary operating parts

Cylinder Guard - a protective cylinder mounting device

Cylinder Key - a broad generic term including virtually all keys for pin and disc tumbler locks

Cylinder Lock - any lock that is operated by a cylinder key

Cylindrical Lock Set - a bored lock set whose latch or bolt locking mechanism is contained in the portion installed through the cross-bore


Deadbolt - a bolt, which requires a deliberate action to extend, and which resists end pressure in the unlocking direction when fully extended

Deadlock - a lock which incorporates a deadbolt

Deadlocking - 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 - a latchbolt with a deadlocking mechanism

Decode - to determine a key combination by physical measurement of a key and/or cylinder parts

Degree of Rotation - 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.

Delayed Action Closer - one which has a specfic hold-open interval before moves a door toward the latching position

Dimple Key - a key whose cuts are drilled or milled into its blade surfaces. The cuts normally do not change the blade silhouette.

Door Closer - a device designed to regulate the closing of a door automatically by various means

Door Puller - a tool designed to open a safe deposit box by forcibly pulling the door and breaking the lock

Door Viewer - a device with one or more lenses, mounted in a door at eye level, which allows a limited view

through a door

Double Bitted Key - a key typically bitted on two opposite surfaces

Double Locking - of or pertaining to a lock with one or more bolts with different functions, typically a latch and a deadbolt

Double Throw Bolt - a deadbolt that has two distinct extended positions, both of which are deadlocked

Drawback Lock or Latch - a latch/lock whose latch is disengaged by pushing or pulling an actuator toward the hinge side of the jamb

Drill Point - the exact measurement of the location used to drill a locked up container to effect an opening

Dummy - pertaining to any type of non-active device applied for aesthetic purposes

Duplicate Key - any key reproduced from a pattern key

Dust Cover - a device designed to prevent foreign matter from entering a mechanism through the key-way


Electric Strike - an electro-mechanical strike, which secures or releases the latch via applied current

Electronic Access Control - access control that uses electricity

Emergency Code - in an electronic lock, a factory-set or user-set code or combination that will open the lock a predetermined number of times

Emergency escape mechanism - an exit device for a vault

Engineers Key - a selective master key which is used by maintenance personnel to operate many locks under different master keys in a system of three or more levels of keying

Entry/Exit Delay - an alarm or access control feature which allows a specific time lapse between the activation of a switch and the activation of a secondary component

Escutcheon - a surface mounted trim which enhances the appearance and/or security of a lock installation

Espagnolette - a top and bottom locking system with hooks at either end which rotate to draw a door or window fully closed

Exit Device - a door lock/latch mechanism which releases in the direction of exit travel via a bar or panel extending across the major width of the door

Exit Door - 1. a door which has no provision for ingress, 2. a door which fills some or all the code requirement for safe egress of the occupant load from a building or portion of a building

Extractor Key - a tool which normally removes a portion of a two-piece key or blocking device from a key-way


Face Plate - the finished, removable plate which covers the front of some locks

Factory Original Key - the cut key furnished by the lock manufacturer for a lock or cylinder

Fail Safe - a feature of a security device designed to release, for safety purposes, during a power loss

Fail Secure - a feature of a security device designed to remain locks for security purposes during a power loss

Finish - a material, coloring and/or texturing specification

Fire Alarm - a system designed to detect and report conditions, which may indicate presence of a fire

Fire Door - a door constructed to provide a specific degree of fire protection

Fire Door assembly - any combination of a fire door, frame, hardware and other accessories, that together provides a specific degree of fire protection to the opening

Fire Exit Hardware - exit devices, which may legally be installed, on fire doors. Distinguished from other exit devices because it:

1.is labeled for both fire and panic and;

2.has no means of locking the latch in a retracted position

Fireman's Key - a key used to override normal operation of elevators, bringing them to the ground floor

First Generation Key - a key which was duplicated using a factory original key or a code original key as a


Floor Safe - a security container designed for mounting below floor level with the top surface flush with the finished floor

Flush Bolt - a non-keyed deadbolt, with a one piece escutcheon/faceplate, typically mounted flush to door surfaces

Forced Entry - entry or bypass techniques which leave obvious damage to the lock or enclosure

French Doors - a set of double doors composed of many small glass panes and narrow stiles


Garage Door Lock - a rim lock mechanism designed for use on an overhead door, which mechanism has a spring loaded bolt which automatically locks the door's bolt mechanism

Gate - a notch cut into the edge of a tumbler to accept a fence or sidebar

Grand Master Key System - a master key system which has exactly three levels of keying

Great Grand master Key System - a master key system which has exactly four levels of keying


Handed - pertaining to hardware which is manufactured only for application on doors with a specific orientation

Handle Set - a complete lock or latch assembly which incorporates a pitcher handle

Hard Plate - a tempered barrier placed between the lock and the outside of a safe to inhibit drilling

Hasp - a hinged metal strap designed to be passed over a staple and secured in place

High Security Cylinder - a cylinder which offers a greater degree of resistance to drilling or other forms of forcible entry and one or more of the following: picking, impressioning, or key duplication

High Security Key - a lock operating device which offers additional defense against its duplication, and/or provides integral features precluding bypass/neutralization of a lock

Hold Open - a function of self latching hardware which allows a lock to be set in a non-latching mode. A function of a door closer, or separate hardware device, which allows the door to be retained in an open position

Hold Back - a function of some self latching locks which allows selective retention of the bolt to prevent latching when the door is closed

Hollow Metal Door - typically a door made of sheet metal on all surfaces and lightly reinforced to make it rigid

Hook Bolt - a lock bolt shaped in the general outline of a hook. Normally used on sliding doors or where spreading of the frame and door is a possible attack.

Hybrid Locking System - a locking system which derives its security from two or more different technologies operated by the same key in one device, e.g. mechanical/electronic, mechanical/magnetic, etc.


Jamb - the vertical components of a door frame

Jimmy - "to jimmy" a door is to open it by means of force.


KA - Keyed alike

KD - keyed different

Keep - recess a bolt or latch with sit in when lock is locked.

Key - a properly combinated device which is, or most closely resembles, the device specifically intended by the lock manufacturer to operate the corresponding lock

Key Blank - any material manufactured to the proper size and configuration which allows entry into the key-way of a specific locking device and may then be bitted to become an operating key for the device

Key Cabinet - a cabinet with hooks, velcro, or other means designed to store keys systematically

Key Coding machine - a key machine designed for the production of code keys. It may or may not also serve as a duplicating machine.

Key Cut Profile - the shape of a key cut, including the cut angle and the out root shape

Key Duplication Machine - a key machine which is designed to make copies from a pattern key

Key Extractor - a tool designed for use to remove a broken or stuck key from a lock

Key Gauge - a usually flat device with a cutaway portion indexed with a given set of depth or spacing specifications. It is used to help determine the combination of a key.

Key Holder - a person to whom a key has been issued

Key in Knob Cylinder - a cylinder used in a key-in-knob lock set

Key in Knob Lock Set - any lock set with a key operated cylinder in one or more knobs

Key Lock - pertaining to a device operated by a mechanical key, as opposed to combination, electronics, etc.

Key Machine - any machine designed to cut keys, See also "key coding machine" and "key duplicating machine."

Key Manipulation - manipulation of an incorrect key in order to operate a lock or cylinder

Key Override - 1. a provision allowing interruption or circumvention of normal operation of a combination lock or electrical device

Key override - 2. adj. of or pertaining to such a provision, as in "key override cylinder"

Keyed Alike - of or pertaining to two or more looks or cylinders which have or are to have the same combination. They may or may not be part of a keying system

Keyed Different - of or pertaining to a group of locks or cylinders, each of which is or is to be combinated differently from the others. They may or may not be part of a keying system.

Keyed Random - of or pertaining to a cylinder or group of cylinders selected from a limited inventory of different key changes. Duplicate bittings may occur.

Key Hole - the opening through which a non-cylinder key must pass to enter a lock

Key Way - 1. the opening in a lock or cylinder which is shaped to accept key bit or blade of a proper configuration

Key Way - 2. the exact cross sectional configuration of a key-way as viewed from the front. It is not necessarily the same as the key section.

Kick Plate - a protective plate mounted on the bottom of a door to prevent damage to minimize damage to the door


Laminated Paldock - a padlock whose case is constructed of separate plates usually riveted together

Latch - a mechanical or magnetic door fastener which can automatically keep a door, gate, etc., closed

Latch - 2. v. engagement of a latch when a door, gate, etc. is pushed or pulled closed

Latch Bolt - a spring actuated bolt, normally with one or more beveled surfaces, which, when aligned with the strike, engages it automatically

Latch Guard - a plate or combination of interlocking pieces designed to block access to the edge of a latch when the door is shut

Leaf - 1.One half or section of a hinge 2. One door in a set of double doors 3. One section of a multiple section door

Lever - a part in a mortice lock. usually 5 lever in a UK insurance approved mortice lock, 2 or 3 levers in internal mortice locks. known collectively as a "lever pack"

Lock - any device which prevents access or use by requiring special knowledge or equipment

Lock Bumping - a picking technique that utilizes a configured key forcefully impacted into the key-way

Lock-in - of or pertaining to a combination lock that is inoperable because the last number of a combination is set in the forbidden zone

Lock Out - any situation in which the normal operation of a lock or cylinder is prevented

lock Set - a locking device, complete with trim, mounting hardware and strike

Locksmith - a person with the knowledge and ability to select, install, service and bypass all the components of an electrical or mechanical lock


Magnetic Contact - an electrical switch activated by magnetic attraction or repulsion

Magnetic Latch - a latch which uses magnetic force to stay engaged with its strike

Magnetic Stripe - a thin layer of material consisting of oriented ferromagnetic oxide particles held together by a resin binder and bonded to a non-magnetic surface such as paper or plastic

Manipulate - a dialling process typically used with combination locks to determine operational status of the lock, potential combinations or attempt to free the mechanism

Manipulation - a opening method for mechanical combination locks which uses the tolerances of that lock to determine an opening combination.

Manipulation Proof - a combination lock with features designed to prevent determining the combination without physical attack

Manufacturer Reset Code - in an electronic lock, a factory-set or user-set code or combination that will restore the factory default settings

Master Blank - a key blank used in a complementary key-way lock, on which only the master key combination is intended to be cut

Master Code - in an electronic lock, a factory-set or user-set combination that must be used before programming the lock

Master Disc - a special disc tumbler with multiple gates to receive a sidebar, see also "master pin" #1, see also "stepped tumbler".

Master Key - 1. a key which operates all the master keyed locks or cylinders in a group, each lock or cylinder usually operated by its own change key

Master Key 2 v. to combinate a group of locks or cylinders such that each is

operated by its own change key as well as by a master key for the entire group, 3. n. an automotive key which

operates all or most locks on a vehicle where there is also a valet key employed

Master Key System - 1. any keying arrangement which has two or more levels of keying

Master Key System - 2. a keying arrangement which has exactly two levels of keying

Master Keyed - 1. of or pertaining to a cylinder or group of cylinders which are or are to be combinated so that all may be operated by their own change key(s) and by additional key(s) known as master key(s) 2. a warded lock whose warding has been designed to allow different hierarchies of keys to operate

Metal Besk Lock - a cabinet lock with a vertically sliding bolt located at the rear of the cylinder

Milling Cutter - a key machine cutter with relatively coarse pitch teeth as opposed to a rotary file cutter

Mis-cut - of or pertaining to a key which has been cut incorrectly 2. n. a mis-cut key

MK - master key

MK'd - master keyed

Mortise - 1. v. to prepare by removing stock material from the edge of a door, drawer, frame or opening to create a recess which allows the flush fit or insetting of relevant lock or other hardware, 2. n. the cavity prepared by mortising, 3. adj. of or pertaining to a locking device designed to fit in a mortise preparation

Mortise Cylinder - a threaded cylinder typically used in mortise locks of American manufacture

Mortise Exit Device - an exit device designed for mortise installation

Mortice Lock Set - a lock set the case of which is designed to fit in a mortise in the edge of a door or drawer

Motion Alarm Lock - a security locking device which audibly alerts upon sensing motion

Movement - a mechanical, electronic or electro-mechanical timer, designed to inhibit the final unlocking of a combination lock or timelock

MP - manipulation proof

MR - manipulation resistant

MS - maximum security

MPL - Multi point lock, as used on UPVC doors in the UK. a lock which has more than one bolt which are thrown and withdrawn simultaneously, often in more than one direction

Mushroom Pin - a pin tumbler, usually a top pin, which resembles a mushroom. It is typically used to increase pick resistance


Neck - (of key) 1. the portion of a bit key between the shoulder and the bit(s) 2. the portion of a cylinder key between the shoulder and the bow

Negative Locking - locking achieved solely by spring pressure or gravity which prevents a key cut too deeply from operating a lock or cylinder

Night Latch - a rim mounted auxiliary latch bolt

Non Handed - pertaining to hardware that is manufactured in a way, which allows installation on doors of any orientation without requiring modification or adjustment to accommodate the door orientation

Non Original Key Blank - any key blank other than an original

Non Removable Key - a key which has one or more cuts on it which trap the key in the lock upon insertion

Non Reversible - door hardware whose hand cannot be changed in the field


Original Key Blank - a key blank supplied by the lock manufacturer to fit that manufacturer's specific product

Overhead Concealed Closer - a closer designed for installation out of view in the door header area

Overhead Stop - a door stop which contacts the door near the top

Overlifting - 1. a picking technique using a blank key to raise the tumblers to the top of the key-way

Overlifting - 2. a lock defeat process that uses a comb attack to bypass the normal locking combination

Overlifting - 3. a process that moves a spring loaded tumbler beyond the operating point

Override Code - in an electronic lock, a factory-set or user-set combination that will always open the lock

Override Combination - in certain locks with a user changeable combination, a second combination which allows access at all times. It is usually factory set and may not be field changeable.


Paddle Handle - a type of actuator which is relatively flat and operates the mechanism when pivoted on an axis near one end

Padlock - a detachable and portable lock with a shackle which locks into its case

Panic Button - any switching device in an alarm system designed to be activated by a person in a panic situation. It creates an immediate alarm condition

Paracentric - 1. of or pertaining to a key-way with one or more wards on each side projecting beyond the vertical centre line of the key-way to hinder picking 2. of or pertaining to a key blank made to enter such a key-way

Parallel Arm - a type of door closer and/or closer mounting which leaves the arm generally parallel to the door face when closed

Passage Set - a latch set

Passive anti theft system - an RFID security system used by Ford which enables the vehicle's ignition system when a properly recognized transponder key is validated

Passive Inferred Device - a device used to detect motion by detecting changes in heat

Passive re Locking Device - a device that places its bolts only upon attack to the safe or lock

Patented Unrestricted key-way - a specific key-way which is sold without restriction by a lock maker, but which retains patent protection against non-original key blank makers

Pattern Key - 1. an original key kept on file to use in a key duplicating machine when additional keys are required,

Pattern Key - 2. any key which is used in a key duplicating machine to create a duplicate key

Peep Hole - a small lens or opening which allows a limited view through a door

PIN - personal identification number, a series of numbers and/or letters associated with a particular individual as a means of identification

Pick - 1. a tool or instrument, other than the specifically designed key, made for the purpose of manipulating tumblers in a lock or cylinder into the locked or unlocked position through the key-way, without obvious damage.

Pick - 2. to manipulate tumblers in a keyed lock mechanism through the key-way, without obvious damage, by means other than the specifically designed key

Pick Gun - a machine designed to impact all of the bottom pins of a pin tumbler lock at exactly the same time and thereby bounce the top pins beyond the shear line

Pick Key - a type of manipulation key, cut or modified to operate a lock or cylinder

Pin - to install pin tumblers into a cylinder and/or cylinder plug, see also "pin tumbler

Pin Chamber - the corresponding hole drilled into the cylinder shell and/or plug to accept the pin(s) and spring

Pin Change - a combination lock that requires manually relocating the fly(s) to change a combination

Pin Kit - a type of keying kit for a pin tumbler mechanism

PIR - Passive infer-red

Plug - the part of a cylinder which contains the key way, with tumbler chambers usually corresponding to those in the cylinder shell

Plug Follower - a tool used to allow removal of the cylinder plug while retaining the top pins, springs, and/or other components within the shell

Plug Holder - a holding fixture which assists in the loading of tumblers into a cylinder plug

Plug Retainer - the cylinder component which secures the plug in the shell

Plug Spinner - a tool which rotates a picked cylinder plug so quickly in the desired direction that it cannot lock during its rotation

Pull Handle - trim for gripping to apply pulling force to a door

Push Plate - a generally flat and commonly rectangular trim mounted for hand contact to push open a door

Push Button Lock - a self contained lock with controls that must be pressed in a specific pattern or sequence to open the lock


Rake - a picking technique that attempts to use quick withdrawal of the pick to set the tumblers

Random Master Keying - any undesirable process used to master key which uses unrelated keys to create a system

Ratchet Lock - any lock which incorporates a ratchet device allowing locking in more than one position

Rated - of or pertaining to a product's compliance with one or more recognized standards such as UL.

Read - to decode a lock combination visually without disassembly of the lock or cylinder

Reader - a device used in an access control system to interrogate an electronic, magnetic or optical type of credential

Reference Position - usually a numerical designation for a tumbler position within a lock or a cut position on a key, typically counted from the stop

Rekey - to change the existing combination of a cylinder or lock

Relocking Device - any device intended to prevent normal opening of a safe as a result of an attack, two types are typically used, internal and external

Remote Release - a mechanism for permitting the unlocking of any lock device at a distance from the device

Removable Core - one whose design limits its installation to one or more specific types of housing or shell from a given manufacturer

Removable Cylinder - a cylinder which can be removed from a locking device by a key and/or tool

Removable Shackle - referring to a type of padlock which is unlocked by removing the shackle from the case

Repin - to replace pin tumblers, with or without changing the existing combination

Reset Code - in an electronic lock, a factory-set or user-set code or combination that will restore all factory default settings except the current reset code and the audit trail

Restricted - of or pertaining to a key-way and corresponding key blank whose sale and/or distribution is limited by the lock manufacturer in order to reduce unauthorized key proliferation

Reverse Key-Way - a key-way shape that is a mirror image of another

Reverse Strike - a strike used for rim mounted hardware used on reverse bevel doors

Reversible - pertaining to hardware that is manufactured in a way, which allows field assembly or adjustment to accommodate installation on doors with different orientations

Reversible Key - a usually symmetrical key which may be inserted either way up to operate a lock

RF - Radio frequency

RFID - Radio frequency identification

RH - Right hand

Rim Cylinder - a cylinder typically used with surface applied locks and attached with a back plate and machine screws. It has a tail piece to actuate the lock mechanism

Rim Lock - a lock or latch typically mounted on the surface of a door or drawer

Rose - a usually circular escutcheon


Safe - a substantial, secure container with varying degrees of security and/or fire resistance, used to store valuables against fire or theft

Safe Deposit - a typically key accessed container that requires dual key operation, usually located inside a vault

Safe Deposit Function - an operational characteristic of a lock which requires two separate keys working in tandem to open the lock

Safe Deposit Lock - a lock that typically requires two separate keys to access a container

Safe Door - that portion of a safe used to gain access to the contents of the safe in a normal day to day manner

Sash Lock - a type of door or window lock

SDB - Safe deposit box

Second Generation Duplicate - a key reproduced from a first generation duplicate

Self Closing - pertaining to doors or covers which have a continuous force applied in the closing direction

Semi Automatic Key Machine - a machine capable of duplicating keys with limited manual operations

Service Code - in an electronic lock, a factory set or user set code or combination that will open the lock one


Shackle - 1. the part of a padlock, which passes through an opening in an object or fits around an object and is ultimately locked into the case 2. the portion of a restraint which fits around the wrist, ankle, neck, waist or thumb

Shank - 1 the part of a bit key between the bow and the stop; or, if there is no shoulder stop, the part between the bow and the near side of the bit, 2. a smaller diameter portion of a knob that is positioned between the larger portion of the knob and the rose or the door surface

Sheer Line - a location in a cylinder at which specific tumbler surfaces must be aligned, removing obstruction(s) which prevented the plug from moving

Shim - 1. n. a thin piece of material used to unlock the cylinder plug from the shell by separating the pin tumblers at the shear line, one at a time 2. v. to unlock a cylinder plug from its shell by using a shim

Shoulder - a projection from a key that can be any key stop other than a tip stop, see also "bow stop". Some shoulders on keys serve no functional purpose.

Shoulder Stop - one that serves as a stop to position the key in a lock or cylinder

Shrouded Shackle - a shackle which is protected from cutting or tampering by design or by the use of secondary shields Simple latch - a non-deadlocking latch

Simultaneous Retraction - a feature which allows retraction of both the deadbolt and latchbolt in the same operation

Skeleton Key - any non-cylinder key whose bit, blade, and/or post is cut away enough to allow it to enter and turn in locks with different ward arrangements

Slim Jim - a narrow strip of spring steel used to bypass the cylinder and unlock vehicle doors

Spindle - a component which transfers rotary motion from outside a lock or latch case to an inner mechanism

Split Spindle - a multi-piece spindle which allows a knob or lever to be installed on only one side of a door

Strike - a bolt receptacle typically mounted in the door jamb or the floor

Strike Reinforcer - a metal plate mounted behind a strike, using long screws to secure it to the door frame.


Tail Piece - an actuator attached to the rear of the cylinder, parallel to the plug, typically used on rim, key-in-knob or special application cylinders

Talon - the part of a lever lock bolt that is relieved to allow the key to enter and move the bolt.

Tamper Resistant Fastener - any one of several screws or nuts which have a specialized head, requiring a special access tool for removal

Tamper Switch - a sensor that signals when someone attempts to access the mechanism of a security device

TCP/IP - the system networks use to communicate with one another

Template - a pattern used to mark cutout locations for hardware installation

Thermal Lance - an instrument, used for cutting with a pure oxygen feed, that uses itself and the material being cut as fuel

Throw - the distance a bolt or latch projects from the faceplate or case of a lock in the extended position

Thumb Turn - a lock with a thumb piece to actuate the latch, a actuator which can be turned by thumb and forefinger

Thumbturn Cylinder - a cylinder with a turn knob rather than a key-way and tumbler mechanism

Time Delay - a feature which prevents operation until a set amount of time has elapsed. Activation normally begins when access, egress or other unlocking is desired.

Time Delay Lock - a lock that has a mechanism for preventing unlocking until a specific amount of time has passed

Tow (of a shackle) - that part of the shackle, which may be removed from the padlock body

Tolerance - the deviation allowed from a given dimension

Touch Bar - a type of exit device actuator which typically does not pivot and retracts the bolt with a minimum of pressure

Touch Pad - 1. an exit device actuator with a paddle shape 2. a remote door opener activator, typically electric or electronic, which facilitates handicap access

2 in 1 Pick - a tool designed to open lever locks where bolt pressure and lever manipulation are applied simultaneously


Un Combinated - 1. of or pertaining to a cylinder which is or is to be supplied without keys, tumblers and springs 2. of or pertaining to a lock, cylinder or key in which the combination has not been set

Under Lifting - a process that moves a spring loaded tumbler to a point short of the operating point to form a shear line

USB Key - a hardware key connected to a USB port


Valet Key - an automotive key that operates all locks except storage compartments, on a vehicle where there is also a master key to operate all locks

VATS - Vehicle Anti-Theft System

VATS Key - a key for some General Motors vehicles which contains a resistor chip that must be qualified by the vehicle in order to run


Wafer Tumbler - 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

Walk in Vault - a vault with a man door and open floor space inside

Wall Vault/Safe - a safe installed in a wall so that only the door and a frame is visible

Ward - a usually stationary obstruction in a lock or cylinder which prevents the entry and/or operation of an incorrect key

Ward Cut - a modification of a key which allows it to bypass a ward

Warded - having one or more wards

Warded Key - a key with ward cuts only, typically a bit key, flat steel key or corrugated key

Window Bug - an alarm system component designed to detect breaking glass


Yale (Linus Jr) - The American inventor of the pin tumbler mortise lock and its replaceable cylinder component.