The Lock Glossary - Lingo and Terminology 101

Welcome to the World of Locksmith Lingo...

Locksmith Lingo can be a very confusing language for the general public and many terms may differ from person to person. While most terms are self-explanitory, there are many other terms that can mean many different things to different people. We hope to help clarify many of the words locksmiths use in order to help you determine exactly what they're attempting to explain regarding your locks and/or security.

ANSI is short for American National Standards Institute. The American National Standards Institute is a private non-profit organization that oversees the development of voluntary consensus standards for products, services, processes, systems, and personnel in North America. These standards ensure that the characteristics and performance of products are consistent, that people use the same definitions and terms, and that products are tested the same way. ANSI also accredits organizations that carry out product or personnel certification in accordance with requirements defined in international standards. Many commercial doors require an ANSI Strike where most residential doors use a smaller standard strike.

A backset is the measurement from the edge of a door to the center of the hole for installing the door lock. Common measurements for most residential doors are 2-3/8", 2-3/4", 3-3/4" and 5" backsets. Many modern residential latches come with an adjustable backset to accommodate the more common backsets. For commercial doors the most common measurements are 7/8", 31/32" 1-1/8" and 1-1/2" backsets.

The "bitting" is the lock manufacturers specific depths of pins within a lock cylinder that creates a shear line to match the depths on the key for proper lock operation. If the bitting on the key does not match the bitting inside of the lock then the lock will not open.

The Cylinder is comprised of many different parts, such as the plug, the bible or shell that houses the top pins and springs, and the tailpiece that drives the latch or bolt to retract and unlock your door.

The term "deadbolt" or "deadlock" is used in many commercial, industrial and residential applications. When the key is turned to the locked position the "bolt" that enters the strike is deadlocked into position so it cannot be forced back with a credit card or knife.

The term "deadlatch" is a springlatch with a small pin behind the latch that when a door is closed the pin will automatically retract into the housing and "deadlock" the springlatch into position so a door cannot be manipulated open with a credit card or a knife. Unlike the springlatch, the deadlatch is designed for exterior doors, where the springlatch is more designed for interior bathroom, bedroom or closet doors.

The term "deadlock" or "deadbolt" is a term used so the door cannot be manipulated open with a credit card or a knife.

Exit Device
An Exit Device is a locking device that allows quick egress by pushing on a crossbar or touchbar that extends across the interior of a door. Exit Devices are also commonly known as "Panic Bars" that can be found on schools and many commercial/industrial applications where public safety is a concern.

The flushbolt is a locking device commonly mortised into the latching side edge of an inactive door between two side-by-side double doors. The active door then locks into the inactive door by a separate latch or bolt. The flushbolt locking pin then enters a hole in the top header or bottom threshold (or both).

The Jamb is the vertical portion of any door frame where the door is hung from hinges on one side and a lock strike is located on the opposing side to secure the door in place.

Handing is the left, right, up or down direction of any locking device. Left and Right indicates the direction of a lock in relation to the opposing hinged side of an application. Handing will also depend on inswinging (LH/RH) or outswinging (LHR/RHR) installation.

Hinges are commonly used to allow doors to swing open or closed. There are many various types of hinges, from residential door hinges to commercial full-length gear hinges, all hinges allow the door to swing in an inward or outward direction. A double hinge is used in saloons and restaurants where the door is allowed to swing in both directions.

The term "key" is the driving force of all locks. The key is the difference between "access denied" and "access granted" through any door or area. Over the years keys are replaced with swipe cards, key fobs, remotes and smartphone capabilities.

The term "keyblank" is simply an uncut key. The keyblank must be cut or duplicated before it will operate a lock.

The "keyway" is the lock manufacturers specific grooves or milling on the sides of a key which allows the key to enter into the lock. The milling or grooves on the key must match that of the lock cylinder.

Masterkey System
The term "master key" or masterkey system is a complex keying system designed for multiple keys to operate multiple doors or areas of large businesses, offices, warehouses, hospitals and schools.

The term "milling" is a term for the shape of grooves cut into a lock manufacturers plug to only allow their key to enter.

The mullion is used between two side-by-side double doors that require latching or locking. The doors are latched and locked into the center mullion rather than into each other, commonly known as "active" and "inactive" double doors. Mullions are mostly found in schools, hospitals or any institution with large wide hallways and corridors.

Nightlatch (NL Function)
The term "nightlatch" is the application of a latch-locking device on a door that keeps the door locked when closed where a key must always be used to enter. Nightlatches are used on residential Rimlocks as well as commercial Exit Device applications.

The "plug" is the core of a lock cylinder where the key enters the lock. The plug is shaped to match the milling or grooves on the key and also holds the bottom pins that match the specific depths and spacings of the key.

"Rekey" or "Rekeying" is the service of removing the tumbler pins, wafers or discs from a lock and installing new pins, wafers or discs. The old key will no longer operate the lock and is a much more cost effective way of "changing your locks" to new keys instead of having to replace the entire lock.

See ReKey.

The word "sash" is a term used to describe any movable frame. Found mostly on doors and windows.

The "shearline" is the interface between the lock plug (yellow) and the lock housing (green). The shear line is created when the correct depth of lock pins (blue and red) coincide with the depths on a properly cut key to allow the lock plug to turn. Without the correct shearline the key will not turn.

The "strike" is attached to the jamb on the frame that holds the latch or bolt in place when the door is closed or locked. Applications may also include "Electric Strikes" when powered will lock or unlock the door.