A-Z List of Locksmithing Terminology [Updated]

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Locksmithing Terminology, Definitions & Phrases 2021 [Updated]

locksmithing terminology
A basic understanding of locksmithing terminology is helpful for everyone.

Locksmithing is a specialized trade and the vocabulary associated with it is not well-known to the general public.

While we use locks and keys everyday, the many industry-specific terms for different types of locks and other security components may trip us up.

Whether you are a locksmith in training or an everyday person interested in the intricacies of locksmithing, the following list of common locksmithing terminology will help you better understand the mechanics behind various security methods.

Master Locksmithing: An Expert's Guide to Master Keying, Intruder Alarms, Access Control Systems,...
49 Reviews
Master Locksmithing: An Expert's Guide to Master Keying, Intruder Alarms, Access Control Systems,...
  • Phillips, Bill (Author)
  • English (Publication Language)
  • 416 Pages - 09/17/2007 (Publication Date) - McGraw-Hill Education (Publisher)

Anti-thrust bolt

A spring bolt which cannot be pushed back once it has shot out. It can be removed with a key or a knob.

Anti-thrust plate

Overlapping metal plates fitted to doors that open outward. These prevent access to lock bolts.   


Molding that covers the gap between a pair of meeting doors. 


A plate to which moving parts of a lock or latch are attached. 


The part of a key which is cut to match levers or pins. This differentiates keys from each other. 


A key that is only partly made. It is shaped to fit a keyhole but does not have notches in its blade to allow it to operate a lock.  


The part of a key that is held in the fingers when the key is inserted. 

Burglar bars

Steel bars cut to fit within window frames.

Cabinet lock

A generic term for any lock used on furniture, such as cupboards, drawers, boxes, etc. 


A vertical measurement between the center of a keyhole and the center of the follower hole, relates to upright and sash locks. 


Houses the pins, top pins, or disc tumblers and springs within the cylinder body. 

Cylinder key

A key with a bow and long blade that has V cuts enabling the operation of pins and drivers in a pin tumbler mechanism. 


A square ended bolt of a lock that is moved into locking and unlocking positions by a key on the outside of a door and a thumb turn on the inside of the door.

Disc tumblers

Small discs in a disc tumbler mechanism which provide different combinations. 

Disc tumbler lock 

A lock containing discs rather than pin tumblers. 

Flush bolt

A door bolt that can be recessed flush with the edge of a door.


The part of a lock through which bolts protrude. The part that is attached to a door. 

Hasp and staple

A two piece fastening for a door or box that requires a padlock. The hinged piece is the hasp, which fits over the staple. The staple is attached to the body of the object.

Hinge bolts

Steel protrusions fitted into the hinge side of a door. These fit into corresponding holes in the door frame and protected against forced attacks. 


Possesses only one bolt to latch/fasten a door. Does not lock.


A flat, moveable detainer in a lock that is moved by a key.

One-sided lock 

A lock with only one keyhole that is usually operated from the outside only. 


The part of a pin-tumbler cylinder in which a key is inserted and turned.


The distance a spring bolt moves under the action of its spring. 


Obstructions inside a lock case to prevent the use of the wrong key. Offer very little security. 

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