Door and Hardware Industry Glossary

You might think a door is simple but, particularly in commercial construction, it is anything but. The terms are numerous and critical in understanding the material and services in the architectural door and hardware industry.


Active Door (in a pair of doors)-The leaf that opens first and the one to which the lock is applied.
AHC-Indicates that the individual so identified is a qualified Architectural Hardware Consultant and member of the Door and Hardware Institute.
Anti-Friction Bearing-Any bearing having the capability of effectively reducing friction.
Anti-Friction Latch Bolt-A latch bolt designed to reduce friction when the bolt starts to engage the lock strike.
Architectural Hardware-Term applied to all hardware used in building construction but particularly that used on or in connection with doors, windows, cabinets and other movable members.
Armored Front-A lock that consists of two plates: the under plate is fastened to the case and is unfinished; the finish plate is fastened to the under plate and when in place covers the cylinder set screws, thus protecting them from tampering. Used on mortise locks.
Armor Plate-A plate similar to a kick plate but covering the door to a greater height, usually 40″ (1040mm) or more from the bottom.
Astragal-A molding or strip whose purpose is to cover or close the gap between the edges of a pair of doors. Some types overlap, others meet at the center line of the gap. (See Coordinator)
Auxiliary Dead Latch -A supplementary latch that automatically deadlocks the main latch bolt when the door is closed. (Also called Deadlocking Latch Bolt)


Back Check-Optional feature in hydraulic door closers slowing the opening swing of the door somewhere between 60 degrees and 85degrees of opening. Designed to protect an object behind the door. Not intended to act as an overhead stop.
Backset (of a lock)-The horizontal distance from the face of the lock to the center line of knob hub keyhole or cylinder. (Measured from the high side of a beveled door.)
Backset (of a hinge)-The distance from the edge of the door to the hinge.
Ball-Bearing Hinge -A hinge equipped with ball bearings between the hinge knuckles to reduce friction. (See Anti-Friction Bearing)
Bevel (of a door)-The angle of the lock edge in relation to the face of the lock stile. Standard bevel is 1/8″ in 2″ (3.2mm in 50.8mm). If otherwise detailed, it must be so noted in ordering locks.
Bevel (of a lock)-A term used to indicate the direction in which the latch bolt is inclined: regular bevel for doors opening in, reverse bevel for doors opening out.
Bevel (of a lock front)-The angle of a lock front when not at right angle to the lock case, allowing the front to be applied flush with the edge of a beveled door.
Bit (of a key)-The projecting blade, cut in a manner that actuates the tumblers and permits the lock bolts to be operated.
Bored Lock (or Latch)-Lock or latch whose parts are intended for installation in holes bored in a door.
Box Strike-A strike that also provides a complete housing to protect the bolt openings.
Builders’ Hardware-See Architectural Hardware
Butt (Hinge)-A type of hinge designed for mortising into the edge of the door and into the rabbet of a door frame.


Cam (of a cylinder)-A rotating piece attached to the end of the cylinder plug to engage the locking mechanism.
Cane Bolt-A heavy cane-shaped bolt with the top bent at right angles; used on the bottom of doors.
Case (of a lock)-The box containing the lock mechanism.
Casement Hinge-A hinge to swing a casement window. The term is often used to describe a hinge designed to throw the sash out far enough to permit cleaning the outside of the glass from the inside of the room on an outward-swinging casement.
CDC-Indicates that the individual so identified is a Certified Door Consultant and member of the Door and Hardware Institute.
Chain Bolt-A spring bolt actuated by a chain attached to the spring bolt for application at the top of the door.
Chain Door Fastener-A device that limits the opening of a door by means of a chain.
Changes (Key)-The different bittings or tumbler arrangements in a series of locks.
Checking Floor Hinge-A device placed in the floor that combines top and bottom pivots for hanging the door with a controlledspeed closing mechanism.
Continuous Hinge (also called Piano Hinge)-A hinge designed to be the same length as the moving part to which it is applied, for example, the lid covering the keyboard of a piano.
Coordinator-A device used on a pair of doors to ensure that the inactive leaf is permitted to close before the active leaf. Necessary when an overlapping astragal is present and exit devices, automatic or self-latching bolts are used with closers on both door leaves.
Cremone Bolt-A device of surface application that, by a turn of knob or lever handle, locks the door or sash into the frame, top and bottom.
Cup Escutcheon-A door plate, for use on sliding doors, having a recessed panel to afford finger hold and to contain a flush ring and sometimes a cylinder, all being flush with the surface of the plate.
Cylinder (of a lock)-The cylindrical-shaped assembly containing the tumbler mechanism and the keyway, which can be actuated only by the correct keys.
Cylinder Collar-A plate or ring used under the head of a cylinder.
Cylinder Lock-A lock in which the locking mechanism is controlled by a cylinder.
Cylindrical (locks and latches)-A term used to describe bored locks, which have a cylindrical case into which a separate latch bolt case fits.
Cylinder Screw-The set screw that holds a cylinder in place by preventing the cylinder from being turned after installation.


Deadbolt (of a lock)-A lock bolt having no spring action nor bevel, and which is operated by a key or a turn piece.
Deadlock-A lock equipped with a deadbolt only.
Deadlocking Latch Bolt-A latch bolt incorporating a plunger that is held in a retracted position when a door is closed, thus preventing the bolt from being retracted by end pressure
Dogging Device-As used in exit devices, a mechanism that fastens the cross bar in the fully depressed position and retains the latch bolt or bolts in a retracted position, thus permitting free operation of the door from either side.
Door Bolt-A manually operated rod or bar attached to a door providing means of locking.
Door Closer Bracket-A device whereby a door closer may be installed on the frame rather than directly on the door.
Door Closer or Check-A device combining a spring for closing and a compression chamber into which the liquid or air escapes slowly, thus providing a means of controlling the speed of the closing action.
Door Holder-A device that holds a door open at one or more selected positions.
Door Pivot-A hinging device embodying a fixed pin and a single joint. Most types include lateral fastening.
Door Stop-A device to stop the swing or movement of a door at a certain point. Also an architectural term defining that part of a door frame against which the door closes.
Double-Throw Bolt-A bolt that can be projected beyond its first position into a second, or fully extended one, thus providing extra security.
Drawer Roller-A device used to ease the sliding of a drawer open or shut, usually with a metal or fiber wheel rotating in a metal frame.
Drawer Slides-A mechanism employing guides and rollers that guide and support the drawer, permitting easy operation.
Drivers-The upper set of pins in a pin tumbler cylinder which, when activated by the springs, project into the plug until raised by insertion of the key.
Drop Escutcheon (or Key Plate)-One having a pivoted plate that covers the keyhole.
Drop Ring-A ring handle attached to a spindle that operates a lock or latch. The ring is pivoted but remains in a dropped position when not in use.
Dummy Cylinder-A mock cylinder without any operating mechanism for use where effect is desired.
Dummy Trim-Trim only, without lock; usually used on the inactive door in a pair of doors.
Dust-Proof Strike-A strike with a spring plunger that completely fills the bolt hole when the bolt is not projected.
Dutch Door Bolt-Device for locking together the upper and the lower leaves of a Dutch door.


Edge Plate-An angle or channel-shaped guard used to protect the edge of a door.
Edge Pull-A pull mortised into the edge of a sliding door.
Elbow Catch-A spring-loaded device embodying a rocker arm and angle strike, for locking the inactive leaf of a pair of cabinet locks.
Electric Strike-An electrical device that permits releasing of the door from a remote control.
Escutcheon (Elongated)-A plate long enough to span a lock case and having holes for knob bushing, bit key, cylinder, turn knob and similar operating members as required.
Escutcheon (Key)-See Key Plate
Exit Device-A door-locking device designed to grant instant exit by pressing on a cross bar that releases the locking bolt or latch.
Extension Flush Bolt-A flush bolt in which the connection between bolt head and operating mechanism is by means of a rod inserted through a hole bored in the thickness of the door.
Extension Link-A device used to provide long backsets in bored locks.


Face (of a lock)-The exposed surface that shows in the edge of a door after installation. (See Front)
Fast Pin Hinge-One in which the pin is fastened permanently in place.
Finish Builders’ Hardware-Hardware that has a finished appearance as well as a functional purpose and that may be considered a part ot the decorative treatment of a room or building. Also termed Architectural Hardware, Finish Hardware and Builders’ Hardware.
Fire Exit Bolt-See Exit Device
Floor Closer-A closing device installed in the floor under a door.
Floor Hinge-A combined pivot hinge and closing device set either in the floor or in the bottom of the door. It may be spring type only or may be combined with liquid control.
Flush Bolt-A door bolt so designed that when applied it is flush with the face or edge of the door.
Flush Cup Pull-A pull mortised flush into a door, having a ring pull that folds flat into the cup of the pull.
Flush Ring-A flush door pull mortised in a door, having a ring pull that folds flat into the cup of the pull.
Foot Bolt-A type of bolt applied at the bottom of a door and arranged for foot operation. Generally the bolt head is held up by a spring when the door is unbolted.
Friction Catch-Any catch which when it engages a strike is held in the engaged position by friction.
Friction Hinge-A hinge designed to hang a door and hold it at any desired degree of opening by means of friction control incorporated in the knuckle of the hinge.
Front (of a lock)-The plate through which the latching or locking bolts project. (See Face.)


Grand Master Key-A key that operates locks in several groups, each of which has its own master key
Guard Bar-A series of two or more cross bars generally fastened to a common back plate to insure protection of glass or screen in a door.


Hand (of a lock, etc.)-Indicates the direction of swing or movement, and/or locking security side of a door.
Handed (locks, etc.)-Indicates that the article is for use only on doors of the designated hand.
Harmon Hinge-A hinge designed to swing a door into a pocket at a right angle with the frame.
Hasp-A fastening device consisting of a loop and a slotted hinge plate, normally secured with a padlock.
Hinge-Two plates joined together by a pin and attached to a door and its frame whereby a door is supported and is enabled to swing or move.
Hinge Stile (of a door)-The stile to which the hinges are applied as distinguished from the lock stile.
Horizontal Spring Hinge-A spring hinge mortised horizontally into the bottom rail of a door and fastened to the floor and head frame with pivots.
Hub-The part ot a lock through which the spindle passes to actuate the mechanism.


Inactive Door (or leaf)-That leaf of a pair of doors that does not contain a lock, but is bolted when closed, and to which the strike is fastened to receive the latch or bolt of the active door.
Indicator Button-A device used in connection with a hotel lock to indicate whether or not the room is occupied.
Integral (locks and latches)-A term used to describe a type of mortise lock having a cylinder in the knob.
Invisible Hinge-A hinge so constructed that no parts are exposed when the door is closed.


Keeper-Synonymous with Strike.
Key Change-The combination of cuts in a key that enable it to operate the lock for which intended.
Key Plate-A small plate or escutcheon having only a keyhold.
Keyway-The aperture in lock cylinders that receives the key and closely engages with it throughout its length.
Kick Plate-A protective plate applied on the lower rail of the door to prevent the door from being marred.
Knob-A projecting handle for operating a lock.
Knob Shank-The projecting stem of a knob into which the spindle is fastened.
Knob Top-That part of the knob that the hand grasps.
Knuckle-The enlarged part of a hinge into which the pin is inserted.


Latch Bolt-A beveled spring bolt, usually operated by a knob, handle or turn.
Leaf (of a pair of doors)-One of the two doors forming a pair of doors.
Letterbox Back Plate-A plate, similar to a letterbox plate, attached to the inside of a door to allow the passage of mail.
Letterbox Plate-A plate attached to the door with an opening to permit insertion of mail.
Lever Handle-A horizontal handle for operating the bolt(s) of a lock.
Lever Tumbler-Flat tumbler having a pivoted motion actuated by the turning of the key and controlling the locking function.
Lip of a Strike-The projecting part on which the latch bolt rides.
Lock Rail (of the door)-The horizontal member of a door intended to receive the lock case.
Lock Set-A lock, complete with trim, such as knobs, escutcheons or handles.
Lock Stile (of a door)-The stile to which the lock is applied as distinguished from the hinge stile.
Loose Joint Hinge-A hinge having but two knuckles; the pin is fastened permanently to one knuckle, the other contains the pinhole, whereby the two parts of the hinge can be disengaged by lifting. These hinges are handed.
Loose Pin Hinge-A hinge having a removable pin to permit the two parts of the hinge to be separated.


Magnetic Catch-A cupboard catch that uses a magnet to hold the door closed.
Master Key-Operates any quantity of cylinders of different individual key changes.
Masterkeying-An arrangement of cylinders having individual key changes, which permits them all to be operated by a simple key called a master key
Mono Lock-See Preassembled Lock
Mop Plate-A narrow plate similar to a kick plate, of sufficient height to protect against the swish of the mop.
Mortise-A cavity made to receive a lock or other hardware; also the act of making such a cavity.
Mortise Bolt-A door bolt designed to be mortised into a door rather than applied to its surface.
Mortise Lock (or Latch)-A lock designed to be installed in a mortise rather than applied to the door’s surface.
Mullion-A fixed or movable post dividing an opening vertically.


Nightlatch-An auxiliary lock having a spring latch bolt and functioning independently of, and providing additional security to, the regular lock of the door.


Olive Knuckle Hinge-A paumelle hinge with knuckles forming an oval shape.
Overhead Concealed Closer-A closer concealed in the head frame with an arm connecting with the door at the top rail.


Panic Exit Device-See Exit Device
Paracentric-A term used in connection with cylinder plugs having projections on the sides of the keyway that extend beyond the vertical center line of the keyway.
Paumelle-A style of hinge embodying a single joint of the pivot type, generally of modern, or streamlined design.
Pin Tumblers-Small sliding pins in a lock cylinder, working against coil springs and preventing the cylinder plug from rotating until the pins are raised to the proper alignment by bitting of key.
Pivot-See Door Pivot
Plug (of a cylinder)-The round part containing the keyway and rotated by the key to transmit motion to the bolt(s).
Preassembled Lock-A lock that has all parts assembled as a unit at the factory and which, when installed in a rectangular notch cut into the door edge, requires little or no disassembly.
Prison Lock-A heavy lock designed especially for use on jail cells.
Push Plate-A plate applied to the lock stile to protect the door against soiling and wear.


Quadrant (Dutch Door)-A device for fastening the upper and the lower leaves of a Dutch door.


Rabbet-A term used to describe the abutting edges of a pair of doors or windows so shaped as to provide a tight fit. One half of the edge projects beyond the other half, usually 1/2″. Also used to define that portion of a door frame into which the door fits.
Rabbeted Lock (or Latch)-A lock in which the face conforms to the rabbet found on a rabbeted door.
Rail (of a door)-A horizontal member that joins the stiles. May be exposed as in a paneled door, or concealed as in a flush door.
Reinforcing Unit-A metal, box-shaped reinforcement used in a metal door in which a bored lock is to be installed to provide both vertical and horizontal latch support.
Reverse Bevel-See Bevel
Reversible Lock-A lock which, by reversing the latch bolt, can be used by either hand. On certain types of locks, other parts must also be changed.
Rigid Lock-See Preassembled Lock
Rim-A term indicating articles of hardware designed for application to the surface of doors and windows.
Roller Latch-A friction door latch employing a roller latch head under spring tension, which engages a strike having a recess formed to receive the roller.
Roller Strike-A strike having a rolling member at the point of latch bolt contact to minimize friction.
Rose-A trim plate attached to the door under the knob. It sometimes acts as a knob bearing.
Rounded Front-A lock or bolt front conforming to the rounded edge of a double-acting door. The standard radius is 4″ (101.6mm).


Sash Balance-A spring device used to counterbalance the weight of a window sash or other vertical sliding part.
Sash Center-A pivoted support for transom or sash and comprised of two parts, one of which contains a pivot, the other a socket for the pivot.
Sash Chain-A metal chain adapted for use with a sliding sash, attached to the sash and to the counterbalancing sash weight.
Sash Cord-Cord or rope used similarly to sash chain and in place of chain.
Sash Cord Iron-A small metal holder inserted in the edge of the sash, to which sash cord or sash chain is attached.
Sash Fast-A fastener attached to the meeting rail of double-hung windows.
Sash Lock-A sash fast with a locking device controlled by a key.
Sash Pole-A wood or metal pole to which a sash pole hook is attached.
Sash Pole Hook-A metal hook attached to a wooden or metal pole used to lower or raise a transom or sash beyond hand reach.
Sash Pulley-A pulley mortised into the frame of a double-hung sash frame over which the sash cord or sash chain passes.
Sash Socket-A metal plate containing a hole or cup to receive a sash pole hook.
Sash Weight-A weight used to balance sliding sash, usually of cast iron or, if conditions require, of lead.
Screen Door Latch-A small locking or latching device used on screen doors and operated by a knob or a lever handle.
Screwless Knob-A knob attached to a spindle by means of a special wrench as distinguished from the more commonly used side knob screw.
Screwless Rose-A rose with concealed method of attachment.
Secret Gate Latch-A surface-applied latch operated by a concealed button or other device; usually used on office gates.
Shank (of a knob)-The projecting stem of a knob into which the spindle is fastened.
Shelf Pin-A pin for supporting a shelf; also called a shelf support or shelf rest.
Shutter Operator (also called a Shutter Worker)-A device incorporating a hinge and a method of opening or closing a shutter by means of a crank or turn from inside without opening window.
Side Knob Screw-A set screw used to fasten a knob to a spindle.
Signal Sash Fastener-A sash-fastening device to lock double-hung windows that are beyond reach from the floor. It has a ring for a sash pole hook. When locked, the ring lever is down; when the ring lever is up, it signals by its upright position that the window is unlocked.
Spindle (of a knob)-The bar or tube connected with the knob or lever handle that passes through the hub of the lock or otherwise engages the mechanism to transmit the knob action to the bolt(s).
Split Astragal-An astragal that is split through the middle, allowing each door leaf to operate independently.
Spring Hinge-A hinge containing one or more springs to move the door into the desired position. It may be either single or double acting.
Stile (of a door)-A vertical member of the door structure; each door has two: a lock stile and a hinge stile.
Stop (of a lock)-The button, or other small device, that serves to lock the latch bolt against the outside knob or thumb piece or unlock it if locked. Another type holds the bolt retracted.
Store Door Handle-A heavy grip or pull mounted on sectional or elongated plates and provided with a thumb piece to operate the latch trip of a store door lock.
Strap Hinge-A surface hinge on which one or both leaves are of considerable length.
Strike-A metal plate or box that is pierced or recessed to receive the bolt or latch when projected. Sometimes called Keeper.
Surface Hinge-One having both leaves surface-applied.
Swinging Latch Bolt-A bolt that is hinged to a lock front and is retracted with a swinging rather than a sliding action. Sometimes called Hinged Latch Bolt.
Swivel Spindle-A spindle having a joint midway in its length to permit the knob at one end to be made rigid by the stop works while the other end is free to operate.


T Handle-A cross handle for actuating the bolt of a lock and used in place of a knob.
T Hinge-A surface hinge with the short member attached to the jamb and the long member attached to the door.
Template Hardware-A term indicating any item of hardware that is made to template; that is, exactly matching the master template drawing as to spacing of all holes and dimensions.
Thimble-The socket or bearing attached to an escutcheon plate in which the end of the knob shank rotates.
Three-Point Lock-A device sometimes required on three-hour fire doors to lock the active leaf of a pair of doors at three points.
Threshold-A strip fastened to the floor beneath a door, usually required to cover the joint where two types of floor material meet.
Throw (of a deadbolt or latch bolt)-Measurement of the maximum projection when bolt is fully extended.
Thumb Piece (of a handle)-The small pivoted part above the grip of a handle to be pressed by the thumb to operate a latch bolt.
Transom Bar-That part of a door frame that separates the top of a door or a window from the bottom of the transom.
Transom Catch-A fastener applied to a transom and having a ring by which the latch bolt is retracted.
Transom Chain-A short chain used to limit the opening of a transom; usually provided at each end with a plate for attachment.
Transom Lift-A vertically operated device attached to a door frame and transom by which the transom may be opened or closed.
Tubular Lock (or Latch)-A type of bored lock.
Tumbler-A guard or obstruction that prevents operation of a bolt except by insertion of the proper key.
Turn Piece-A small knob, lever or tee turn with spindle attached for operating the deadbolt of a lock or a mortise bolt. Also termed Thumb Turn.
Two-Point Latch-A device sometimes required on three-hour fire doors to lock the inactive leaf of a pair of doors at top and bottom.


Unit Lock-See Preassembled Lock
Universal-A term used to describe a lock, a door closer or other device that can be used on doors of any hand without change.


Vertical Spring Pivot Hinge-A spring hinge mortised into the heel of a door and fastened to the floor and head with pivots.


Ward-An obstruction projecting from the lock case of side of a keyhole intended to prevent entrance or rotation of an improperly cut key.