Locksmith Glossary of Terms

Locksmith information courtesy of Always In Service. Learn some of the terms before requesting service. It will help you understand what work is being preformed by Always In Service’s locksmith technicians.

We’ll show you the basics first, after the basics there is a full Glossary of Locksmith Terms by letters.

Basic Locksmith Glossary of Terms:

(or: bit of key) is the part of the key that actually engages the tumblers to activate the lock. Bittings are often represented as a code which instructs how a key is to be cut by a locksmith. The bitting is usually a series of integers (e.g. 372164) that is usually translated from a key code chart or from a bitting code list and the use of specially designed key machines. One American manufacturer, Eagle Lock Company, used letters exclusively for bitting codes.

Each digit in the bitting corresponds to a different cut or notch on the key and represents the depth at which the key must be cut. Each number in a bitting represents not only the depth of which the key blank is to be cut, but also the location of the cut on the key blank. Depending on the maker, the bitting sequence can be from bow-to-tip (the bow being the larger, handle portion of the key), or can be from tip-to-bow as is in the case of Best Locking Systems and Assa Abloy. A smaller number is typically a shallower cut on the key, but not always. Assa bitting codes are reversed, where the higher the digit, the shallower the cut.

Locksmiths can cut to the code given when supplying a lost key or making a new restricted key copy.

Angularly bitted:
This is a type of key where the individual cuts are designed to engage chisel-pointed pins in high-security locking systems manufactured by Medeco and Emhart. These angled cuts are designed to lift each tumbler to a predetermined height to the shear line and to rotate them to a specific angle to engage a sidebar mechanism (Medeco) (this is also used in Schlage Primus) or to line up an interlocked pin to such a position to where it would allow the plug to rotate (Emhart).

Bolt Stump:
A bolt stump is a rectangular part of a lock located above the talon, and passes through the slot in the levers as the bolt moves. This part is welded or riveted onto the lathe in some earlier locks. Modern lock manufacture allows this to be machined in. Most are directly cast into the blank and then milled smooth for final use.

Change Key:
A change key is a key on the lowest level of a master keying system. Change keys are also referred to as day keys. Typically change keys are issued to personnel that require access to one or two areas in a facility. By definition, a change key is not a master key. Change key can also refer to the specialized keys used to change the combination setting of a combination lock. Change key can refer to a special key on the “Sabre” Keyboard, located to the right of the “P” key, and can also be typed by doing ALT+0164, or using ‘@’ in Turbo Sabre. Sabre is a Global Distribution System (GDS), used by travel agencies to book flights, hotel reservations, car rentals, etc.

Key Code:
A key code is a series of alphanumeric characters used by locksmiths to create a key. There are two kinds of key codes: blind codes and bitting codes.

Blind codes:
These are codes that require a chart or computer program to translate the blind code to a bitting code, which is used to create the actual key. Most key codes are blind codes, and publication of code books or software are restricted to licensed locksmiths in most jurisdictions for security reasons. Some locksmiths also create their own blind coding systems for identifying key systems they installed, or for customer identification and authorization in high security systems. Example: 23N7 (General Motors) or X2100 (Nissan) are examples of blind codes used for automotive ignition keys. Many computer and manually generated master keying charts also utilize blind codes for identifying individual change keys and masters within the system.

Bitting code:
The translated blind code which the locksmith actually uses to cut each cut on a blank key. Example: padlock blind code W123 translates to bitting code 25313, to which the locksmith would cut the key with his code machine by setting it to 25313. Experienced locksmiths might be able to figure out a bitting code from looking at a picture of a key. This happened to Diebold voting machines in 2007 after they posted a picture of their master key online, people were able to make their own key to match it and open the machines.

Key Blank:
A key blank (sometimes spelled keyblank) is a key that has not been cut to a specific bitting. The blank has a specific cross-sectional profile to match the keyway in a corresponding lock cylinder. Key blanks can be stamped with a manufacturer name, end-user logo or with a phrase, the most commonly seen being ‘Do not duplicate’. Blanks are typically stocked by locksmiths for duplicating keys. The profile of the key bow, or the large, flat end, often references an individual manufacturer. Despite common belief, keys stamped with “Do not duplicate” or “It is unlawful to duplicate this key” are, with few exceptions, perfectly legal to duplicate. Some key blank manufacturers strictly restrict the sale of their own blanks. Some blanks are made only in small volumes and are not widely available.

Key Relevance:
In master locksmithing, key relevance is the measurable difference between an original key and a copy made of that key, either from a wax impression or directly from the original, and how similar the two keys are in size and shape. It can also refer to the measurable difference between a key and the size required to fit and operate the keyway of its paired lock. No two copies of keys are exactly the same, unless they were both made from key blanks that are struck from the same mould or cut from the same duplicating/milling machine with no changes to the bitting settings in between. Even under these favorable circumstances, there will be minute differences between the two key shapes, though their key relevance is extremely high. In all machining work, there are measurable amounts of difference between the design specification of an object, and its actual manufactured size. In locksmithing, the allowable tolerance is decided by the range of minute differences between a key’s size and shape in comparison to the size and shape required to turn the tumblers within the lock. Key relevance is the measure of similarity between the key and the optimal size needed to fit the lock, or it is the similarity between a duplicate key and the original it is seeking to replicate. Key relevance cannot be deduced from a key code, since the key code merely refers to a central authoritative source for designed shapes and sizes of keys. Typical modern keys require a key relevance of approximately 0.03 millimeters (0.0012 in) to 0.07 millimeters (0.0028 in) (accuracy within 0.75% to 1.75%) in order to operate.

Maison Key System:
A Maison key system is a keying system that permits a lock to be opened with a number of unique, individual keys. Maison key systems are often found in apartment building common areas, such as main entrance or a laundry room where individual residents can use their own apartment key to access these areas. Unlike a master key system, where each individual lock has one individual operating key and one common master key, Maison lock is designed to be operated by every key within the system. Because of the inherent lack of security in the Maison key system, some jurisdictions prohibit the use of Maison key systems in apartment and condominium complexes. In such locations, access is usually facilitated by either a high-security, key-controlled system or the use of electronic access control systems such as a card reader.

Master key:
A master key operates a set of several locks. Usually, there is nothing special about the key itself, but rather the locks into which it will fit. These locks also have keys that are specific to each one and cannot operate any of the others in the set. Locks that have master keys have a second set of the mechanism used to operate them that is identical to all of the others in the set of locks. For example, master keyed pin tumbler locks will have two shear points at each pin position, one for the change key and one for the master key. A far more secure (and more expensive) system has two cylinders in each lock, one for the change key and one for the master key. Larger organizations, with more complex “grandmaster key” systems, may have several masterkey systems where the top level grandmaster key works in all of the locks in the system.

A practical attack exists to create a working master key for an entire system given only access to a single master-keyed lock, its associated change key, a supply of appropriate key blanks, and the ability to cut new keys. This is described in Cryptology and Physical Security: Rights Amplification in Master-Keyed Mechanical Locks.

Locksmiths may also determine cuts for a replacement master key, when given several different key examples from a given system.

Master keys may also refer to a door-breaching shotgun used by military and law enforcement. It utilizes a specially designed shotgun shell containing 40-50 grams of powdered steel and can either be a riot shotgun, combat shotgun, or an rifle mounted such as the KAC Masterkey or M26 Modular Accessory Shotgun System.

Control key:
A control key is a special key used in removable core locking systems. The control key enables a user with very little skill to remove from the cylinder, quickly and easily, a core with a specific combination and replace it with a core with a different combination. In Small Format Interchangeable Cores (SFIC), similar to those developed by Frank Best of the Best Lock Corporation, the key operates a separate shear line, located above the operating key shear line. In Large Format Removable Cores (LFRC), the key may operate a separate shear line or the key may work like a master key along the operating shear line and also contact a separate locking pin that holds the core in the cylinder. SFIC’s are interchangeable from one brand to another, while LFRC’s are not.

Transponder key:
Transponder keys may also be called “chip keys”. Transponder keys are automotive ignition keys with signal-emitting circuits built inside.

When the key is turned in the ignition cylinder, the car’s computer transmits a radio signal to the transponder circuit. The circuit has no battery; it is energized by the radio signal itself. The circuit typically has a computer chip that is programmed to respond by sending a coded signal back to the car’s computer. If the circuit does not respond or if the code is incorrect, the engine will not start. Many cars immobilize if the wrong key is used by intruders. Chip Keys successfully protect cars from theft in two ways: forcing the ignition cylinder won’t start the car, and the keys are difficult to duplicate. This is why chip keys are popular in modern cars and help decrease car theft.

Many people who have transponder keys are not aware of the fact because the circuit is hidden inside the plastic head of the key. On the other hand, General Motors produced what are known as VATS keys (Vehicle Anti-Theft System) during the 1990s, which are often erroneously believed to be transponders but actually use a simple resistor, which is visible in the blade of the key. If the value of the resistor is wrong, or the key is a normal key without a resistor, the circuit of the car’s electrical system will not allow the engine to be started.

Double-sided key:
A double-sided key is very similar to a house or car key with the exception that it has two sets of teeth, an upper level standard set of teeth and a lower, less defined set of teeth beside it. This makes the double-sided key’s profile and its corresponding lock look very similar to a standard key while making the attempt to pick the lock more difficult. Four-sided key A four-sided key (also known a cross or cruciform key) has four sides, making it not only harder to duplicate and the lock harder to pick but also more physically durable.

Paracentric key:
A paracentric key is designed to open a paracentric lock. It is distinguishable by the contorted shape of its blade, which protrudes past the centre vertical line of the key barrel. Instead of the wards on the outer face of the lock simply protruding into the shape of the key along the spine, the wards protrude into the shape of the key along the entire width of the key, including along the length of the teeth. Internal cut key An internal cut (also known as “Sidewinder” or “Laser Cut”) key has a rectangular blade with a wavy groove cut up the center of the face of blade, at constant depth.

Typically the key has an identical wavy groove on the back of the blade, making it symmetrical so it works no matter which way it is inserted. Also referred to as the inner profile or sidewinder. These keys must be cut by special key cutting machines made for them.

Abloy key:
Abloy keys are cut from a metal half-cylinder. The cuts are made at different angles, so when the key is turned in the lock it rotates each disk a different amount. Nearly all the houses in Finland use Abloy keys, although they are also widely used in various locales worldwide. These locks are considered very secure and almost impossible to pick.

Dimple key:
A dimple key has a rectangular blade with various cone-shaped dimples drilled into the face of the blade at various depths. Typically the lock has 2 rows of pins that match up with 2 rows of dimples. Typically the key has the same dimple pattern on the back of the blade, making it symmetrical so it works no matter which way it is inserted. Kaba and Dom are manufactures of dimpled keys. These keys are relatively easy to not only pick, but also make impressions of.

Skeleton Key:
A skeleton key (or passkey) is a very simple design of key that usually has a cylindrical shaft (sometimes called a shank) and a single, minimal flat, rectangular tooth or bit. Skeleton keys are also usually distinguished by their bow, or the part one would grasp when inserting the key, which can be either very plain or extremely ornate. A skeleton key is designed to circumvent the wards in warded locks. Warded locks and their keys provide minimal security and only a slight deterrent as any key with a shaft and tooth that has the same or smaller dimensions will open the lock. However, warded keys were designed to only fit a matching lock and the skeleton key would often fit many. Many other objects that can fit into the lock may also be able to open it.

Due to its limited usefulness, this type of lock fell out of use after more complicated types became easier to manufacture. In modern usage, the term “skeleton key” is often misapplied to ordinary bit keys and barrel keys, rather than the correct definition: a key, usually with minimal features, which can open all or most of a type of badly designed lock. Bit keys and barrel keys can be newly-minted (and sold by restoration hardware companies) or found in antique stores.

They were most popular in the late 1800s, although they continued to be used well into the 20th century and can still be found today in use, albeit in vintage homes and antique furniture.

Tubular key:
A tubular key (sometimes referred to as a barrel key when describing a vintage or antique model) is one that is designed to open a tubular pin tumbler lock. It has a hollow, cylindrical shaft that is usually much shorter and has a larger diameter than most conventional keys. Antique or vintage-style barrel keys often closely resemble the more traditional skeleton key but are a more recent innovation in keymaking. In modern keys of this type, a number of grooves of varying length are built into the outer surface at the end of the shaft. These grooves are parallel to the shaft and allow the pins in the lock to slide to the end of the groove. A small tab on the outer surface of the shaft prevents the pins in the lock from pushing the key out and works with the hollow center to guide the key as it is turned. The modern version of this type of key is harder to duplicate as it is less common and requires a different machine from regular keys. These keys are most often seen in home alarm systems, vending machines, laptop locks, and bicycle locks, in the United States. These keys typically come in seven and eight-pin versions as well as miniature versions which are used on computers. Tubular keys were invented by the Ace lock company in Chicago.

Zeiss key:
A Zeiss key (also known as a Cruciform key) is a cross between a house key and a tubular key. It has three sets of teeth at 90 degrees to each other with a flattened fourth side. Though this type of key is easy to duplicate, the extra sets of teeth deter lockpicking attempts.

Do Not Duplicate key:
A Do Not Duplicate key (or DND key, for short) is one that has been stamped “do not duplicate” and/or “duplication prohibited” or similar by a locksmith or manufacturer as a passive deterrent to discourage a retail key cutting service from duplicating a key without authorization or without contacting the locksmith or manufacturer who originally cut the key. More importantly, this is a key control system for the owner of the key, such as a maintenance person or security guard, to identify keys that should not be freely distributed or used without authorization. Though it is intended to prevent unauthorized key duplication, copying DND keys remains a common security problem. There is no direct legal implication in the US for someone who copies a key that is stamped do not duplicate (unless it is an owned key), but there are patent restrictions on some key designs (see “restricted keys”). The Associated Locksmiths of America, ALOA, calls DND keys “not effective security”, and “deceptive because it provides a false sense of security.” United States Code 18 USC Sec. 1704 deals with United States Post Office keys, and 18 USC Sec. 1386 deals with United States Department of Defense keys.

Restricted key:
A restricted keyblank is a keyway and blank for which a manufacturer has set up a restricted level of sales and distribution. Restricted keys are often protected by patent, which prohibits other manufacturers from making unauthorized productions of the key blank. In many cases, customers must provide proof of ID before a locksmith will cut additional keys using restricted blanks. These days, many restricted keys have special in-laid features, such as magnets, different types of metal, or even small computer chips to prevent duplication.

Magnetic key:
A magnetic keyed lock is a locking mechanism whereby the key utilizes magnets as part of the locking and unlocking mechanism. A magnetic key would use from one to many small magnets oriented so that the North / South Poles would equate to a combination to push or pull the lock’s internal tumblers thus releasing the lock. This is a totally passive system requiring no electricity or electronics to activate or deactivate the mechanism. Using several magnets at differing polarity / orientations and different strengths can allow thousands of different combinations per key.

A keycard is a flat, rectangular plastic card with identical dimensions to that of a credit card or driver’s license which stores a physical or digital signature which the door mechanism accepts before disengaging the lock. There are several popular type of keycards in use including the mechanical holecard, bar code, magnetic stripe, Wiegand wire embedded cards, smart card (embedded with a read/write electronic microchip), and RFID proximity cards. Keycards are frequently used in hotels as an alternative to mechanical keys.

Rekeying normally refers to the ability to change a lock so that a different key may operate it. Rekeying is done when a lock owner may be concerned that unauthorized persons have keys to the lock, so the lock may be altered by a locksmith so that only new keys will work. Rekeying is a relatively simple a process of changing the tumbler or wafer configuration of the lock so a new key will function while the old one will not. Rekeying may be done without replacement of the entire lock. Rekeying was first invented in 1836 by Solomon Andrews, a New Jersey locksmith. His lock had adjustable tumblers and keys, allowing the owner to rekey it at any time. Later in the 1850s, inventors Andrews and Newell patented removable tumblers which could be taken apart and scrambled. The keys had bits that were interchangeable, matching varying tumbler configurations. This arrangement later became the basis for combination locks.

Shear Line:
In a cylinder lock, the shear line (also known as the split line in Australia), is where the inner cylinder ends and the outer cylinder begins. When a break in the pin is reached by picking, the pin will “hang” at the shearline due to the space between the inner and outer cylinder. This “imperfection” in the lock mechanism is an unavoidable defect in the manufacturing process that allows for lock picking. Lock picking is a vital part of the locksmithing process as it can grant non-destructive entry to the lock device thus allowing it to be rekeyed instead of being replaced.

Advanced Locksmith Glossary of Terms:



Access – the ability, right, or permission to approach, enter, speak with, or use.

Affordable – that can be afforded; believed to be within one’s financial means.

Appointment – a fixed mutual agreement for a meeting; engagement.

Asset – a useful and desirable thing or quality.

Attract – to draw by appealing to the emotions or senses, by stimulating interest, or by exciting admiration; allure; invite.

Auto – a passenger vehicle designed for operation on ordinary roads and typically having four wheels and a gasoline or diesel

internal-combustion engine.

Available – suitable or ready for use; of use or service; at hand.

Avoid – to keep away from; keep clear of.


Basic – pertaining to, or forming a base; fundamental.

Brass – any of various metal alloys consisting mainly of copper and zinc.

Burglary – the felony of breaking into and entering the house of another at night with intent to steal, extended by statute to

cover the breaking into and entering of any of various buildings, by night or day.


Commercial – suitable for or catering to business or churches rather than private use.

Compatible – able to exist together with something else.

Competitive – decided by competition.

Complicated – difficult to analyze.

Coupon – a printed form, as in an advertisement, to be used as an order blank or for requesting information or obtaining a

discount on merchandise.

Customer – one that buys goods or services.

Cylinder – a cylindrical device for retaining the bolt until tumblers have been pushed out of its way.


Damaged – injury or harm that reduces value or usefulness.

Deadbolt – lock bolt placed or moved into position by the turning of a knob or key instead of by spring action.

Dedicated – wholly committed to something, as to an ideal, political cause, or personal goal.

Describe – to tell or depict in written or spoken words; give an account of.

Development – an act of developing.

Door Closer – a device, usually hydraulic or pneumatic, for controlling the closing of a door and preventing it from slamming.

Door knob – a knob-shaped handle for opening and closing a door.

Double sided deadbolt – double sided deadbolt is a deadbolt that locks from the inside and outside. You would need a key to open it and to lock it from both sides.


Efficient – performing or functioning in the best possible manner with the least waste of time and effort; having and using

requisite knowledge, skill, and industry; competent; capable.

Emergency – a sudden, urgent, usually unexpected occurrence or occasion requiring immediate action.

Estimate – to form an approximate judgment or opinion regarding the worth, amount, size, weight, etc.; calculate approximately.


Forbids – to command (someone) not to do something.

Fresh Installation – drilling and adjustment procedure in order to place a new lock in wood or metal doors where there is no space in the door.


General – of or pertaining to all persons or things belonging to a group or category.

Glossary – a list of terms in a special subject, field, or area of usage, with accompanying definitions.

Guaranteed – a promise or assurance, esp. one in writing, that something is of specified quality, content, benefit, etc., or that

it will perform satisfactorily for a given length of time.


High Security lock – high quality strong lock, provide ultimate protection against any break- in entry methods and tools.


Ignition – the process that ignites the fuel in the cylinder.

Ignition Key – a key that operates the ignition switch of an automotive engine.

Immediate – following or preceding without a lapse of time.

Insist – to be emphatic, firm, or resolute on some matter of desire, demand, intention.

Integrity – adherence to moral and ethical principles; soundness of moral character; honesty.



Key – a small metal instrument specially cut to fit into a lock and move its bolt.

Keyless – requiring no key or keys: a keyless lock operated by a series of push buttons.

Knob – a projecting part, usually rounded, forming the handle of a door, drawer, or the like.

Kwikset – one of the most common brands locks in America for residential structures.


Licensed – formal permission from a governmental or other constituted authority to do something, as to carry on some business or profession.

Lock – a device operated by a key, combination, or keycard and used, as on a door, for holding, closing, or securing.

Lock Change – to take the existing lock in place out and put in a whole new lock in place of the old one.

Lock Install – to place a new lock in, where there was no lock before, consist on drilling a hole in the door.

Locksmith – a person who makes or repairs locks and keys.


Manufacture – To make or process (a raw material) into a finished product, especially by means of a large-scale industrial operation.

Mistake – an error in action, calculation, opinion, or judgment caused by poor reasoning, carelessness, insufficient knowledge.

Mobile – capable of moving or being moved readily.



Option – the power or right of choosing.


Passage Lock – a simple handle that has no locking cylinder. For convenience purposes only.

Pin – a short, straight, stiff piece of wire with a blunt head and a sharp point, used especially for fastening.

Position – condition with reference to place; location; situation.

Potential – possible, as opposed to actual.

Price – the amount as of money or goods, asked for or given in exchange for something else.

Privacy – the state of being private; retirement or seclusion.

Problem – a question to be considered, solved, or answered.

Product – something produced by human or mechanical effort or by a natural process.

Professional – following an occupation as a means of livelihood or for gain.

Provide – to supply or equip.

Providing – to make available; furnish.



Rate – the amount of a charge or payment with reference to some basis of calculation.

Recommend – to praise or commend (one) to another as being worthy or desirable; endorse.

Rekey – using the existing lock to get a new key, where the key that was used before no longer works on the lock.

Reliable – that may be relied on; dependable in achievement, accuracy, honest.

Representative – one that serves as a delegate or agent for another.

Requirements – something that is required; a necessity.

Residential – of or pertaining to residence or to residences.

Rochester – a city in W New York, on the Genesee River.


Satisfaction – an act of satisfying; fulfillment; gratification.

Schlage – one of the most common brands locks in America for residential structures.

Security – freedom from danger, risk, etc.; safety.

Service – an act of helpful activity; help; aid.

Sophisticated – altered by education, experience, etc., so as to be worldly-wise; not naive.

Specialist – one who is devoted to a particular occupation or branch of study or research.

Specific – of a special or particular kind.

Stylish – characterized by or conforming to style or the fashionable standard; fashionably elegant.


Technician – a person who is trained or skilled in the technicalities of a subject.

Testimonial – something given in appreciation of a person’s service or achievement; a tribute.

Thorough – executed without negligence or omissions.

Transponder – a radio, radar, or sonar transceiver that automatically transmits a signal upon reception of a designated incoming signal.

Tumbler – (in a lock) any locking or checking part that when lifted or released by the action of a key or the like, allows the bolt to move.


Unrivaled – having no rival or competitor; having no equal; incomparable.


Value – elative worth, merit, or importance.

VAT System – vehicle anti theft security system that certain models of GM cars are occupied with.

Vendor – a person or agency that sells.


Window – an opening in the wall of a building, the side of a vehicle, etc., for the admission of air or light, or both, commonly fitted with

a frame in which are set movable sashes containing panes of glass.

Workmanship – the art or skill of a workman or workwoman.

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