Locksmith Terms

Every occupation has its own words and phrases specific to that profession. Often consumers can feel a bit intimidated when professionals use phrases not commonly known to the general public.

It’s no different with locksmiths. These terms evolve over time because of the skills and knowledge required to do the job. They are by no means an attempt to keep the consumer in the dark. Nevertheless, professionals sometimes forget that their clients are not familiar with the industry jargon.

In this blog, we’ll introduce some of the words and phrases used by all professional locksmiths in an attempt to help you, the consumer, become familiar with them.


Access control - A device regulating access to an entry or exit.

Anti-thrust bolt - A spring bolt, particularly for a night latch, which cannot be pushed back once it has shot out and locked a door.

Anti-thrust plate - An overlapping metal plate fitted to doors which open out blocking access to the lock bolts.


Birmingham bar - A steel bar fitted to the inside of the door frame on the hinge side to resist kick-in attacks.

Backplate - A plate on the inside of a door through which the cylinder connecting screws and tailpiece is passed.

Bit - The section of a key which enters a lock, which has the key cuts formed in it and which engages the bolt or tumblers of the lock. The bit is called a blade in the case of a cylinder key.

Blank - An unfinished key as it comes from the manufacturer.

Bolt - The part of a lock or latch which closes it by extending from the case or faceplate to engage in the staple, striking plate, link, shackle or other member.

BS 3621 - British Standard Grade certifying the lock fulfills specific security requirements. Locks conforming to this grade display the BS kite mark stamp. Many insurance companies require these lock types for entrance and exit doors.

Bumping - A lock picking technique using a specially designed bump key to open a pin tumbler lock.

Butt Hinge - A rectangular hinge, one half of which is mortised into the edge of a door, the other half into the door jamb, so that both halves touch when the door is closed.


Casement Window - A window with its sash hinged at the side or top.

Code Book - A listing of code numbers and their corresponding combination of key cuts for the locks of various manufacturers. These codes enable a ocksmith to cut a key for a coded lock without an existing key to copy and without having to take the lock apart.

Cylinder lock or latch - Any lock or latch whose mechanism is contained in a cylinder.


Deadbolt - A lock bolt, usually rectangular, that has no spring action, and locks against end pressure when fully projected.

Deadlatch - A latch or nightlatch, with a springbolt which can be locked (or deadlocked) by key or other means.

Deadlock - A lock having only a square-ended deadbolt operable from one or both sides by key, and occasionally from outside only by key, inside by thumb turn. Sometimes operable only from outside and with no inside keyhole, which is designated a single-entry deadlock.

Disc tumbler lock - A cylinder lock having disc instead of pin tumblers.

Door viewer - Optical device fitted through a door to allow observation without opening the door -- also known as a peep hole.

Double cylinder deadlock - A deadbolt lock whose bolt may be operated by a key from either side.


Escutcheon - The key hole cover of a mortice or other similar type lock.

Extractor - Any of a number of thin tools used to remove broken key segments from a lock keyway, often homemade from spring steel wire, crochet hooks, fish hooks, coping saw blades and the like.


Face - The front surface of a lock cylinder perpendicular to the keyway at the point where the key enters the lock.

Fixed Tumbler – A safe deposit lock lever tumbler with an unchangeable setting. Also called a fixed lever or a non-changeable lever. While combination tumblers may or may not be fixed tumblers, guard tumblers and trap tumblers are always fixed tumblers.

Flush Bolt – A locking bolt which, when installed on a door, is flush with the surface of the door.

Four Pin Master Key - a master key for all combinations obtained by progressing four bitting positions.

French Spring – A flat-wire, coiled spring used in French door locks to hold the lever handle horizontal. Also called a gun spring.

Call A-1 Keys for an assessment and estimate. The best money you can spend is securing your property and your family before a problem arises. The financial and emotional cost after a break-in are too high for you to have to pay.


Grade 1 - Locks rated for commercial applications. They meet commercial building requirements. These locks are tested to 800,000 cycles and are vandal resistant which makes them well suited for trouble areas.

Grade 2 - Locks are designed for light duty commercial (interior) and heavy duty residential. Commercially they are good for light duty doors such as offices. They are the preferred grade for residential over grade 3 locks.

Grade 3 - Light duty residential locks. They should never be used for commercial applications. The effective security of grade 3 locks is in high debate among security professionals. Security is not the place to be cheap. Why would you spend $3000 on a flat screen TV and $15 on the cheapest front door lock you can find?

Grip - the knob, lever, thumbpiece, push-pull operator, etc., of any working trim.


Hinge bolts - Fixed steel bolts fitted into the rear edge or hinge side of doors and closing into holes in the door frame, protecting from forced attack on the hinge side of the door.

High Security Lock - A heavy-duty lock that provides more security than other locks. Frustrates picking attempts, thwarts drilling, and often provides key control.

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.


Index (of a combination lock dial) - the mark outside the dial ring of a combination lock used as a reference point.

Interchangeable core - a key removable core which can be used in all or most of the core manufacturer's product line. No tools (other than the control key) are required for removal of the core.


Jackscrew - a threaded rod used for centering and balancing a vault door & frame in position during installation.

Jamb - The inside vertical face of a doorway.


Key code - A series of numbers or digits on a key or lock that specifies or references the particular cuts of the key to operate a lock.

Keyless entry - Method of opening locks without a traditional key. Method can be elecronic or mechanical. For example, numbered keypad, fob, proximity card, magnetic stripe card.

Keyway - The configuration of grooves along the blade of a key. Just as you "can't put a square peg in a round hole," neither can you put any key into any lock. The keyway of the key must coincide with the keyway of the lock. Since a Master-key must enter all the locks of a Master-keyed group of locks, all the locks in the group must have keyways compatible with the Master-key.


Latch - A mechanical device which automatically keeps a door closed.

Lever lock - Lock with levers that are each lifted to the correct level by a bit key or flat metal key to enable the lock to operate.


Manual Dogging - 1. An exit device that requires a physical action to dog it. 2. Using a wrench or a special key to dog an exit device.

Master Key - Opens all locks on the corresponding Master Key System. Individual keys on the system are limited to opening individual locks. Useful for building managers, commercial buildings and property managers.

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


Narrow Stile - Pertaining to aluminum doors with stiles generally between 1-3/4 and 2-3/4 inches wide.


One Shot - of or pertaining to a wire run that has an unobstructed line of sight.

One-Sided Lock (single-entry) - A lock which has a keyhole on one side only.

Pin Tumbler Mechanism - The mechanism incorporated in the cylinder or body of a cylinder pin tumbler lock, latch or padlock.

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

A-1 Keys will be glad to give you an estimate for duplicating your ignition or security keys.


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

Passive Infrared Device - a device used to detect motion by detecting changes in heat pattern key.

Pattern Key - 1. an original key kept on file to use in a key duplicating machine when additional keys are required, 2. any key which is used in a key duplicating machine to create a duplicate key.

Perforated Tumbler - a combination wheel with multiple holes within its diameter for mounting the fly.

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

Pin Tweezers - a tool used in handling tumblers and springs.

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

Push Bump Key - a lock picking key that centers itself after each impact.


Quadrant - a dutch door lock with a bolt that is 1⁄4 of a circle.


Re-Key - Manipulate a lock so that different keys open it.

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

Rim cylinder - The mechanism used in dead bolts that are mounted with screws from the opposite side of the door.

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


Sash lock - A vertical mortice lock, consisting of a latch bolt and a key operated bolt attached to two sashes- usually referring to a window lock.

Spring Bolt - Sometimes called the latchbolt. It is a bolt which can be retracted by pressure into the lock-case and will return to the extended position when pressure is released.

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

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

Standard Key Coding System - an industry standard and uniform method of designating all keys and/or cylinders in a master key system. The designation automatically indicates the exact function and keying level of each key and/or cylinder in the system, usually without further explanation.


Talon - The notch in the bolt tail which the key or other rotating member engages to move the bolt.

Tap - A tool with external cutting threads to cut internal threads in a hole.

Threshold - A piece of wood or stone which lies directly under the bottom edge of a closed door. Also called a sill.

Tumbler - The detainer which must be lifted to allow the lock bolt to move.


UL Listed - listed in a directory as having passed specific Underwriters Laboratories testing.

Unidirectional Cylinder - a cylinder whose key can turn in only one direction from the key pull position.


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 - abbreviation for Vehicle Anti-Theft System: an electronic system in some vehicles which uses a resistor pellet of varying value imbedded in a mechanical ignition key.


Wheel Lock 1. a lock which prevents rotation of a wheel, 2. a lock which prevents removal of a wheel.

Wheel Puller - a tool used to remove the steering wheel from a column.

Wide Stile - pertaining to aluminum and hollow metal or wood doors with stiles 5 inches wide or larger.


X - sym. symbol used in hardware schedules to indicate a cross-keyed condition for a particular cylinder; e.g., XAA2, XlX (but not AX7).

- a component designed to secure cylinders or turn disks in both sides of a mortise lock by means of a single setscrew.

Z-wire - 1. A wire bypass tool with two opposing right angle bends, for retracting a spring latch. 2. A wire tension wrench for the control lug in certain IC padlocks.

We hope this definition of locksmith terms has been useful to you. A-1 Keys would like to remind you that it’s always best to call a professional for any problems or needs you have concerning the security of your home and the security and operation of your vehicle. Trying to get into your locked vehicle on your own can create damage to your car that will cost you more money than calling a professional locksmith who has the skills and tools to get you into your home or vehicle properly. A-1 Keys has all the latest tools and technology to solve your lockout, installation or duplication problems without causing further damage to your property. The best way to insure you do not need to call a locksmith at night, in the rain, or from a lonely stretch of road is to be prepared in advance. Call A-1 Keys to have duplicate keys made now so that you do not compromise your safety in the future. Transponder keys can be made for a much lower price if you have the original. If the original is lost, your costs will go up significantly. If you have lost the key, it is impossible to make a duplicate without the vehicle. It will always cost more to have a locksmith come to your location than it will to take your key to his store and have a duplicate made there. You may also incur towing charges if you can’t get a key made right away. A-1 Keys is your local, professional locksmith. We look forward to serving you.

  • Emergency lockout service
  • Transponder chip keys and remotes replaced
  • All types of automotive locks replaced
  • Broken keys extracted
  • Trunks opened
  • High security ignition keys replaced
  • Ignitions replaced
  • Locks rekeyed
  • Master key system installed
  • High security locks installed or replaced
  • Dead bolts installed
  • Key entry knob installed
  • Door closures installed
  • Panic bars installed
  • Surveillance systems designed & installed
  • Store front locks installed and rekeyed
  • Emergency lockout service
  • Keyless entry system installed
  • Emergency lockout service
  • High security lock installation
  • Security door and gates
  • Rekey and repair locks
  • Garage door remotes
  • Mailboxes rekeyed
  • Safes installed and repaired
  • Combination locks installed
  • Security systems designed & installed