Locksmith Terminology – A Dictionary of Locksmith & Security Terms

15 September 2023by easefix@gmail.com

Discover the functions of each lock component by learning the names of the various lock parts. You may meet your security needs using the Master Locksmiths Association’s glossary of locksmith terminology.

Confused About Type of Locks?

Our article, which details the common types of locks used in homes, might help you determine what kind of door lock you have.


Anti-thrust bolt: A spring bolt, specifically for a night latch, can be withdrawn using a knob or key but cannot be put back once it has shot out and latched a door. A dog inside the latch case often accomplishes this security measure that, when an auxiliary slide is pulled in, inhibits the bolt from being blasted out by falling behind it.

Anti-thrust plate:  a metal plate that overlaps and is installed on outward-opening doors to block access to the lock bolts. A deadlatch that automatically locks (or deadlocks) when the door is closed is known as an automatic deadlatch.


Backplate: the plate permanently affixed to a door and to which a lock or latch’s moving pieces are fastened. Backset the horizontal distance between the centre of the keyhole or follower hole (or both) and the outer face of the outer forend. Known as the “follower backset” or “keyhole backset.”

Barrel Bolt: The typical door bolt has a round shoot with a knob or the equivalent for manual operation, running in a long continuous guide or strap attached by the backplate.

Birmingham Bar: A steel bar is installed on the hinge side of the inside face of a door frame.

Blank (key) or critical blank An incomplete key is one whose shape allows it to fit into a specific type of Lock or latch but whose blade has not yet been notched to open any particular lock.

A bolt is a portion of a lock or latch that extends from the case or forend to engage with the staple, striking plate, link, shackle, or other elements to achieve fastening or engagement.

Bow When using a lock or latch, the portion of a key held in the fingers is used.

B.S. – British Standard Specification The British Standards Institute, the acknowledged U.K. authority for all performance, testing, and manufacturing standards, has authorized and issued this product.

BS3621 The requirements of the British Standard for thief-resistant locks on hinged doors. The ten strict clauses of the specification must be met by locks submitted for certification.

Burglar Bars Cut-to-length steel bars with a typical round or square profile are fastened internally to window frames.


Cabinet lock: a general term that refers to any locks used on furniture components, including cabinets, drawers, chests, boxes, and the like.

Cam: typically a tongue attached to a cylinder lock or latch’s plug end.

Cam lock: a complete locking assembly that takes the shape of a cylinder, with the cam acting as the locking bolt.

Cap (of the Lock): the cover for a detachable lock mechanism.

Casement Door: a pair or single hinged door with nearly complete glass; also known as a French Window.

Casement Window: a window with one or more lights that can be opened on hinges.

Centres: the distance in height between the centre of the keyhole and the center of the follower hole in an upright or sash lock.

Circlip: An open-ended ring that can be sprung into position on a plug or other device to allow rotation but restrict endway movement.

Closed shackle padlock: a padlock with a body constructed to reveal the bare minimum of the shackle when locked. It provides better protection against coercion or the employment of bolt-croppers.

Combination Lock: the name of a keyless combination lock shortened. Remove cabinet lock, a lock for a cabinet or drawer whose flange is set into the edge of the drawer or door.

Cylinder: The cylinder that houses the top pins (drivers), disc tumblers, and springs in the cylinder body has typically an inner coaxial plug.

Cylinder housing: This constitutes the cylinder’s main body or housing when all components are removed.

Cylinder key is used to activate the pins and drivers in a pin tumbler mechanism, with a bow and a long blade with “V” cuts made along the upper edge.

Cylinder lock or latch: any latch or Lock whose mechanism is housed inside a cylinder.

Cylinder rose (or ring): a formed metal disc encircles the cylinder’s exterior face in a cylinder mechanism assembly. It typically protrudes somewhat from the door’s exterior face.


Deadbolt: The square-ended lock bolt that provides fastening is moved by the key in both locking and unlocking directions (though rarely by a thumb turn inside alone). N.B. If used on glass or wood-panelled doors, combining the thumb turn with the deadbolt of any deadlock or Lock meant to offer adequate security is not suggested.

Deadlatch A deadlatch is a latch or nightlatch whose springbolt can be locked (or deadlocked) using a key or another tool.

A deadlock is a lock with a square-ended deadbolt that can be opened by a key from either one or both sides or occasionally from the outside with a key and the inside with a thumb turn. When a deadlock can only be opened from the outside and has no interior keyhole, it is called a single-entry deadlock.

Detainer 1. a general, uncommon name for any component, such as a lever or tumbler, that maintains the position of a lock bolt. 2. This term knows sliding security members in Butter’s System locks.

Differs An acronym for “different combinations” or alterations.

Disc tumblers The little shaped discs (often made of metal) used in the disc tumbler mechanism to create various combinations.

The disc tumbler locks a cylinder lock with disc tumblers rather than pin tumblers.

A Door Closer is a mechanism that automatically closes a gate or entrance after it opens. There are many different kinds available.

Door viewer: A door-mounted optical gadget that allows observation without opening the door.

Double Bitted Key one with a little on the shank’s sides.

Double-handed lock 1. a lock that can be installed either way, right or left, without modification—typically by flipping it upside down. At each keyhole’s end is a circular opening that receives the key’s shank. 2. A cabinet lock with a bolt that may be shot in either direction so that it protrudes from both sides of the case.


Escutcheon: the keyhole cover on a mortise lock or other similar Lock.


Faceplate: a double forend’s outer forend. A metal strip is attached to the inner forend to create a double forend.

Final exit door The exit door must be opened for entry afterward and cannot be locked or bolted. It is frequently the main entryway or the last point of departure.

Flush Bolt: a door bolt that can be flush-recessed into a door’s edge or face.

Forend: The area of the Lock or latch where the bolt(s) protrude and is used to secure the Lock or latch to the door.

Furniture The extra parts required that are screwed to one or both sides of the door to make it possible to operate a lock or latch manually. When equipped with a lock or latch, these items are called locksets or latchsets and might be either a knob, lever handle, pull handle, or push button.


Hasp and staple a two-piece fastener that locks a door or box with a padlock. The hasp, a hinged component, is attached to a box’s door or lid and closes over the staple on the door frame (or other leaf of a pair of doors) or the box’s body. The heads of the fixing screws must be entirely covered when the padlock is locked in place for a hasp and staple to provide actual security; otherwise, the fitting can be removed by removing the screws, providing zero security.

Hinge Bolts To prevent a forced attack on the door’s hinge side, doors are supplied with fixed steel protrusions that fit into holes drilled into the door frame.

Hook bolt: a spring bolt with a pivoting head and a hook-like appearance. These latches or locks are frequently installed on sliding doors.


Jamb: the frame’s vertical support for a door or window. The top rail of a door frame is occasionally called the top jamb.


Key: A tiny, removable device used to operate the Lock, locking latch, or night latch on its own.

The key blank is a key that has only been partially created; its blade has not yet been notched or bitted to operate the lock mechanism, but it has been fashioned to fit into the keyhole of a particular type of Lock or latch.

A keyhole is the opening through which the key is inserted to open a lock or latch. It’s frequently called the keyway, especially as part of a cylinder mechanism.

Key Steps or critical depths: This phrase often means the bolt step and lever step of a key for a lever lock.


Latch a single-bolt product, such as a roller or bevelled spring bolt, that may latch or fasten a door but cannot be locked. However, some varieties, such as locking latches, nightlatches, and deadlatches, can be secured by a key or another device.

Lever: A lock with a flat-shaped, moveable detainer that typically serves as security and differs. To open a lock, the key must move one or more levers. To allow for varied combinations, the belly of the Lever is sliced away at different depths.

Lever mechanism: a lock mechanism with one or more levers as the main feature.

Lever and warded mechanism The lever mechanism has wards added to it, typically to provide a more comprehensive number of differences. The lock’s security is kept the same by installing wards, though. View “Wards”

Lever handle: a piece of lock or latch furniture that operates a lock or latch’s spring bolt instead of a knob, typically mounted on a rose or plate. Most Continental lever handles are not spring-loaded, so when used with British locks or latches, they occasionally tend to sag below the horizontal after a relatively brief period of use unless additional springing is included in the lock action. All British lever handles are spring-loaded to ensure the return to horizontal after use.

Lock: A mechanism that fastens and secures a door, lid, drawer, or other member with one or more bolts or other members; often, but not always, a key is required to operate it.

A Lockable bolt can be fired and locked into place with a different key.

Locking latch: a latch that can be locked or fastened using a key and has a bevelled spring bolt or roller bolt.

Lockset: a lock ready to be fixed to the door and includes all essential accessories, such as a spindle.

Lockset furniture or lock furniture: A lockset minus the Lock.

London strip: a padlock shackle offering more clearance than a typical shackle.

Long shackle: (L.S.) A padlock shackle that offers more clearance than a typical shackle would.

Lubrication: Pin-tumbler cylinders should never be lubricated with oil. The typical lubricant for this mechanism is graphite.


Master Key: a key that can unlock each Lock in a building with master keys.

Master Keyed (locks or latches): a lock or latch that can be opened with a master key and its own backup or servant key.

Mortice: a hole drilled into a door’s thickness on one edge so that a mortice lock or latch can be installed.

Mortice Key: a key with a bow, shank, and bit for opening a lever lock.

Mortice lock (or latch): a lock or latch that is screwed into place via the forend and mortised or let into the thickness of the door from the meeting edge.


Nightlatch: a rim or mortice latch with a bevelled spring bolt or roller bolt that fires when the door is closed and may be opened with a key from the outside and a knob or lever handle from the inside. Generally has a stop knob, slide, or snib to lock down the bolt when fired in the closed position and to keep the bolt retracted even while the key is being turned.


A one-sided lock (single-entry) is a lock that only has a keyhole on one side, generally the outside, making it impossible to open the Lock from either side at the same time. Examples include almost all cabinet locks and all padlocks. One-sided cylinder mortice locks do exist in excellent grade.

One-way action is a move where the following will only look in one direction.


Padlock: a relatively tiny, removable, and transportable lock that is typically, but not always, solely one side key actuated. A circular hinged sliding or swivelling shackle that fits into a hole in a staple, locking bar, or other similar component serves as the locking member.

Panel grilles: Steel grilles that are custom-sized and installed inside, typically with extended diamond mesh, square weld mesh, or decorative infills.

Pin tumbler mechanism: The component of a cylinder lock, latch, or padlock built into the cylinder or body and uses a cylinder pin tumbler mechanism.

Other than padlocks, the cylinder with its coaxial plug—which is under spring pressure and houses the pins and drivers—passes through the thickness of the door. The right key aligns the pins and drivers to create a clear line of intersection between the plug and the cylinder, enabling the plug to rotate and the Lock to be operated.

Anti-pick mushroom drivers are often included in every cylinder, and the system ensures excellent protection against essential interchangeability. For instance, Yale 5-pin cylinders come standard with up to 24,000 combinations.

The suite can contain various locks or latches, so it is also ideal for master keying.

Twelve thousand two hundred differences are available under the master key, and 36 separate sub-suites with a maximum of 2,200 differences each can be offered under the grand master key.

Plug: the area where the key inserts and rotates within the pin-tumbler or disc-tumbler cylinder mechanism. A pin tumbler cylinder’s pins or a disc tumbler cylinder’s discs and springs are stored in it.


Rack Bolt: a bolt with teeth that can be turned by a pinion, typically a door bolt.

Rebate: measuring a rebated lock’s forend’s stepwise decrease or recess.

Rebated (Lock or latch) a mortice lock or latch with a forend precisely designed to match the curvature of the door’s intended meeting edge. Check out “Full Rebated”

Release: A striker that can take several forms and actuated electronically to replace the lock strike.

Rigid grilles: Heavy-duty rods or bar grilles with welded construction are typically installed on the exterior or interior of a structure.

Rim Cylinder: The cylinder with plug, the rose, the connecting bar, two connecting screws, and two keys are usually included in this box.

Rim lock or latch a lock or latch attached to a door’s inside face using screws.

Rose 1. A rose or ring that can be used with latches or cylinder locks. A formed metal disc encircles the outer face of cylinder two. The tiny plate is fastened to the door’s surface with screws and attached to the door’s lever handle or knob.


Safe Lock is a collective term for the key-operated and other safe lock types.

Sash lock: A key-operated bolt and a latch bolt comprise an upright mortice lock.

Sash ward: used in rim and mortice locks, alone or with levers, to obtain or increase the differences. Around the inside of the keyhole, formed metal pieces in a circular pattern are attached.

It works as a keyhole bush as well. To actuate the bolt, the bitted key passes over these wards. When used alone, sash wards offer little protection. Check out “Skeleton Keys”

Shackle: The component of a padlock that has a loop shape and is hinged, sliding, or swivelling. The toe of the shackle emerges when a padlock is unlocked, but the heel stays fixed inside the padlock body.

A double-locking padlock provides the best defence against forcing because two bolts lock outward in opposing directions, one into a recess in the heel of the shackle and the other into the toe of the shackle.

Heel and toe locking is another name for this.

Shear Line: The word refers to the circumference of the plug as measured around the bore of a pin tumbler cylinder.

Shoot 1. A lock bolt’s outward motion and the distance it moves when a spring or key is applied. The throw is a better word for deadbolts; shoot is more specifically used for spring bolts. 2. The portion of a door bolt that slides.

Shoot (of the bolt) the length that a spring bolt travels after being compressed by its spring.

Side Bar: Besides the pin or disc mechanism already in place, this one has a bar that runs along its length and prevents rotation until the mechanism is correctly elevated and may be operated directly by the key.

Side Wards: Bitter keys are designed with notches carved onto the side that allow the key to turn.

Sliding grilles: Steel single- or double-leaf sliding grille gates with top and bottom guide tracks that can be closed with a padlock or built-in Lock.

A sliding Lever is a lever that swings on a pivot rather than one that moves between or on guides.

Spindle: That portion of the door hardware, typically square and fitted to the knob(s) or lever handle(s) to operate the spring bolt, passes through the follower hole.

Spring shackle padlock: a padlock with a snap-lockable shackle that springs open when the Lock is released.

Springbolt:  Occasionally known as the latch bolt. A bolt with a bevelled vertical face shapes the outside of the bolt. It is a bolt that can be put back into the lockcase and automatically revert to the extended position.

Staple 1. an inward-opening door jamb fitting that resembles a box into which the rim latch or lock’s bolt or bolts protrude when the door is closed. (In Scotland and the North of England, it is sometimes called a bosshead. Some staples have lips that can be used as a spring bolt guide.

  1. A piece of a staple and hasp for a padlock. The eye or hole in the staple is where the padlock shackle enters.

Stop knob (snib): Some latches and locking latches have a mechanism that keeps the bolt retracted or deadlocks the bolt when the door is closed.

Striking plate:  referred to as a “striker” on occasion. It consists of a formed flat metal plate with one or more bolt holes fastened to the door frame or jamb into which the bolt or bolts shot. On one side, a formed protruding lip serves as a spring bolt guide. It is utilized with all mortice and latches, rim locks, and latches on outward-opening doors with reversed spring bolts.

Suite (of locks): a group or collection of locks, locking latches, and padlocks of various sorts and modifications combined under a master or grand master key.


Thumb turn: a tiny fitting that opens the deadbolt of a mortice lock by being grasped between the thumb and finger. It shouldn’t be applied to doors with glass or wood panels.

Tie bars: vertical elements of the horizontal bar grille.

Time Lock: a mechanical or electrical timed device that prevents the opening of doors or the activation of locks on safes or strongrooms.


Wards: As the key is cut to pass over the wards and operate the Lock, there are fixed impediments inside the lock case to prevent using the incorrect key. They are occasionally utilized in lever locks to provide more significant differences. Wards provide little security on their own. Look up “Skeleton Key.”

Warded Lock: any padlock or lock with a mechanism that only uses wards. Not advised because of the need for more security.


What are 999 keys?

Bump keys are precisely cut keys that can surpass the security features of conventional tumblers and pin locks. Bump keys are sometimes known as “999 ” since all their ridges are cut in a key-making machine to the deepest possible level (999).

What is the Bible in lock terms?

The area that holds the pins, pin stack springs, and pin stacks is known as the “bible” of a pin tumbler lock. The driving pins for the pin-tumbler lock are inside the Bible. The part of a key with critical cuts on it that engages the Lock’s bolt or tumblers when it is inserted into a lock.

What are the seven primary keys?

The four clefs of the critical signatures of C, G, D, A, E, B, F, and C. In Example 14, the key signature for C major is presented first (without any sharps or flats), followed by each of the flat key signatures in the four clefs: F, B, E, A, D, G, and C major.

What are locksmith tools called?

Most locksmiths frequently employ tension wrenches and key turners for a straightforward lock and critical system. Expert locksmiths frequently employ modern tools, including grinders, milling machines, and cylinder crackers.

Final Thought

In conclusion, a comprehensive understanding of locksmith terminology is essential for locksmith professionals and anyone interested in security. The diverse array of terms covered in this dictionary encompasses the intricacies of locks, keys, and security systems. Whether you’re a seasoned locksmith looking to refresh your knowledge or a novice eager to delve into the locksmithing world, this dictionary is an invaluable resource.

By exploring the definitions and explanations provided here, you can gain insight into the terminology that underpins the locksmith and security industry. From pin tumblers to master critical systems, this dictionary elucidated the terminology locksmiths encounter daily. Moreover, it highlights locksmiths’ vital role in safeguarding our homes, businesses, and assets.

As technology evolves, locksmiths must adapt to new security challenges and innovations. Staying up-to-date with the ever-expanding lexicon of locksmith terminology is crucial for maintaining high professionalism and expertise in this dynamic field.

In sum, this dictionary illuminates the locksmith profession and emphasizes the importance of security in our daily lives. Whether you’re seeking to enhance your knowledge or simply curious about the intricacies of locks and keys, this resource is a valuable reference point for anyone interested in locksmithing and security.



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