Learn locksmith lingo and terms/words used by locksmiths
action The arrangements of live or latch bolts and their accessories in a lock or latch, and how they function.
alike change More than one lock or latch which can be operated by the same key.
all to pass Often referred to as “locks to pass” i.e. a number of locks which can be passed or keyed alike (opened by the same key).
anti-thrust bolt A spring bolt, for a night latch particularly, which cannot be pushed back when it has shot out and fastened a door.
anti-thrust plate An overlapping metal plate fitted to outward opening doors so as to prevent access to lock bolts.
automatic deadlatch A deadlatch, the main bolt of which is automatically locked (or deadlocked) when the door is closed
backplate A plate on the inside of a door through which the cylinder connecting screws and tailpiece is passed.
backset The horizontal distance from the edge of a door to the center of a lockset.
bar (OF LEVER) The part between the pockets which is slotted to allow the bolt stump to pass through.
barrel and curtain This is the full name of a security device fitted in some locks to turn and close the keyhole when the key or any other instruments inserted through the keyhole is turned.
barrel bolt The common kind of door bolt having a round shoot running in a long continuous guide or strap attached to the backplate, the shoot being provided with a knob or the equivalent for operation by hand.
barrel key A key with a bit projecting from a hollow cylindrical shaft.
bathroom lock A lock with a springbolt operable on both sides by furniture, and a deadbolt operable from the inside only, usually by thumb turn.
bi-lock A pin tumber cylinder lock consisting of two parallel rows of pin tumblers and two sidebars operated by a U shaped key.
birmingham bar A steel bar fitted to the inside face of a door frame on the hinge side.
bit key A key with a bit projecting from a solid cylindrical shaft. The bit has cuts to bypass the wards or operate levers in the correct lock.
bit key lock A warded or lever lock that uses bit keys.
bitting A cut, or series of cuts, on the bit or blade of a key.
blade The portion of the key that is inserted into the lock.
blank A key before any cuts have been made.
bolt The part of a lock or latch which provides the fastening or engagement by protruding from the case or forend to engage in the staple, striking plate, link, shackle or other member.
bolt head The portion of a bolt that protrudes beyond the case of forend of a lock.
bolt hole The hole in a case, forend, plate or staple to guide and/or admit the bolt.
bolt stump According to some authorities, this is the name of the part that upstands, usually rectangular in section, on a dead bolt or runner which passes through the slot or gating in the levers as the bolt moves.
bow The handle of the key.
burglar bars Steel bars, usually round or square in profile, cut to length and fixed internally to window frames.
by-pass tool A device that neutralizes the security of a locking device, or its application hardware, often taking advantage of a design weakness.
cabinet lock A generic term to include all locks of any type for use on pieces of furniture, such as cupboards, drawers, chests, boxes and the like.
cam Usually a tongue fixed to the end of the plug of a cylinder lock or latch.
cam lock A lock that has an attached cam that serves as the lock’s bolt. Cam locks are often used on cabinets, file cabinets and drawers.
cap (of the lock) The removable cover to a lock mechanism.
case The housing or body of a lock.
casement door A hinged door or pair of doors almost wholly glazed; often called a French Window.
casement window A window in which one or more lights are hinged to open.
case ward Protrusions that stick out of the sides of the keyway to allow entry of only the correct type of key blank.
chamber The holes in cylinder housings that house top pins (drivers) and springs.
change index The point on a key changeable combination lock dial ring to which the old and new combinations must be dialed when changing the combination.
change key The key that operates one lock in a masterkeyed system.
change key locks These are locks which can be operated by any key chosen from a large number of different keys that have been made for the purpose. The selected key is the only one which will open the lock until a change is deliberately made.
claw blot A type of deadbolt having pivoted claws which swing out sideways when the bolt is shot. Such locks are usually fixed to sliding doors.
clutch headed screw Threaded screws suitable for wood or metal with a shaped head allowing clockwise action to fix but no anticlockwise action to remove
close shackle padlock A padlock, the body of which is built up so that the minimum amount of shackle is visible when locked. It offers improved security against forcing or use of bolt-croppers.
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.
collar The shoulder on the shank of a rim, mortice or bitted key, controlling the point at which the key comes to rest after being fully inserted into the lock. The collar is the datum point from which the key is measured.
combination lock An abbreviation of name for a keyless combination lock.
concealed fixing (of locks or latches) A strong backplate is screwed to the door, the lock case slides over it and is secured in position by two or more grub screws which are concealed whenever the door is closed. This is usually associated with security night-latches.
control key A key used to remove the core from an interchangeable core cylinder.
control shear line The shear line which allows operation of the control lug of an interchangeable core.
control sleeve The part of an interchangeable core retaining device which surrounds the plug.
cover The part of a lock or latch which covers the mechanism and is fixed, usually by screwing, to the case.
cross-bore A hole drilled into the face of a door where a bored or interconnected lockset is to be installed.
cross differ An error situation whereby change keys (servant keys) operate more than one lock when this was not intended.
cross rail The horizontal member of a door.
curtain An abbreviation for barrel and curtain.
cut cabinet lock A cupboard or drawer lock, the flange of which is recessed into the edge of the drawer or door.
cuts A cut, or series of cuts, on the bit or blade of a key.
cylinder Usually the cylinder with inner co-axial plug which houses the pins, top pins (drivers), or disc tumblers and springs in the cylinder body.
cylinder housing With all component parts removed, this forms the main body or housing of a cylinder.
cylinder key A key for use with pin tumbler and wafer tumbler cylinder locks.
cylinder lock or latch Any lock or latch, the mechanism of which is contained in a cylinder.
cylindrical lockset A bored lockset whose latch or bolt locking mechanism is contained in the portion installed through the cross-bore.
cylinder rose (or ring) A shaped metal disc which surrounds the outer face of the cylinder of a cylinder mechanism assembly. It usually stands slightly proud of the outside face of door.
deadbolt A lock bolt, usually rectangular, that has no spring action, and that becomes locked against end pressure when fully projected.
deadlatch A lock with a beveled latch bolt that can be automatically or manually locked against end pressure when projected.
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.
deadlocking Pertaining to any feature which, when fully engaged, resists attempts to move the latch or bolt in the unlocking direction through direct pressure.
deadlocking latch A latchbolt with a deadlocking mechanism.
depth The depth of a cut is measured from the bottom of the blade up to the bottom of a cut. Depths are numbered starting with #0 (or sometimes #1) as the highest depth.
depth key A special key that enables a locksmith to cut blanks made from a particular lock according to a key code.
differs An abbreviation of “different combinations” or changes.
disc tumbler lock A cylinder lock having disc instead of pin tumblers.
door closer A device for closing a door or gate automatically after opening. There are numerous types available.
door viewer Optical device fitted through a door to enable observation without opening the door.
double-acting lever tumbler One which must be lifted a precise amount, neither too little nor too much to allow movement of a bolt.
double-bitted key One with a bit on each side of the shank.
double cylinder Pertaining to a lock with two keyed cylinders.
double cylinder deadlock A deadbolt lock whose bolt may be operated by a key from either side.
double feather spring Two separate feather springs, fitting closely together one inside the other. Alternatively both may be made form one length of material and remain joined at one end. A spring so made is more lively and likely to last longer than a single spring of thicker material.
double locking 1. By introducing a different cam arrangement into the action of a cylinder rim nightlatch it is possible to give a double or deadlocking facility at no extra cost. A simple opposite turn of the key in the outside cylinder deadlocks both bolt and inside knob simultaneously. This gives protection against the bolt-forcing and the glass or wood panel breaking intruder. 2. Also where a lever lock shoots its bolt by more than one turn of the key, thus doubling the distance of its shoot.
drilled-through spindle (for lock furniture) Usually shortened to DT. A spindle with a few holes drilled at each end, one of which accepts the screw passing through the neck of the knob (or lever handle) in the door furniture.
drill-pin (sometimes pin) A fixed stump or pin in a lock onto which the hollow shank of a pipe key fits when inserted to operate the lock.
drivers top pins. The pins in a lock that sit on top of the lower pins and rest against the springs.
drop 1. In drawer, chest, box or similar cabinet locks, the vertical distance from the outside face of the top edge or selvage to the center of the keyhole. Sometimes this term is used for a keyhole cover an a padlock.
Locksmith Terms Glossary E-H
ear of key or shoulder The projecting stop on one or both edges of a pin tumbler or other key near the bow to prevent the key from being pushed too far into the lock.
easy actionA lock is designed so that only light spring pressure is required to move the bolt ; additional spring pressure is required to move the follower and lock furniture. This is necessary especially when lock furniture comprises of lever handles, the handles then return to their correct position.
effective plug diameter
en suite To indicate that locks are incorporated in a master keyed system or keyed alike en-suite.
escutcheon The cover for the key hole of a mortice or similar lock.
face plate The outer of a double forend. A strip of metal fixed to the inner forend, thus forming a double forend.
false notches or false gating 1.The notches in the bar of the levers and the bolt stump of some locks to improve the security against attempted picking.
Cuts or notches which are put in some keys to give the appearance of greater intricacy although they serve no useful purpose.
final exit door The exit door through which entry must later be obtained, and so cannot be bolted. It is usually the front entrance door or final means of exiting.
flat steel key A key which is completely flat on both sides, usually used for warded or lever tumbler locks.
flush bolt A door which can be recessed flush into the edge or face of a door.
follower That part of the latchbolt or springbolt mechanism containing a square hole to admit the spindle (to which furniture is attached) which withdraws the springbolt when turned. It has one or two projections or horns which act on the bolt foot.
forend That part of the lock or latch through which the bolt(s) protrude, and by which the lock or latch is fixed to the door.
four-way lock A rim lock so made that it can be fitted as either a right hand or left hand installation on doors opening either inwards or outwards, without alteration, except that in some types the springbolt may need reversing.
full mortise Pertaining to a method of installation in which only the face plate and trim is exposed. The lock case is installed in a pocket in the door or drawer.
full rebated(lock or forend) A mortice lock or latch with a specially shaped forend and striking plate to suit the shaped meeting edge of a single door which overlaps the door frame or a pair of doors which overlap each other – and such overlap or rebate is at the centre of the door thickness.
full width padbar Usually purpose made, a steel bar spanning the full width opening of a door with supporting brackets or staples fixed to the frame and secured by a padlock.
furniture The additional items needed, which are screwed to one or both sides of the door to enable a lock or latch to be manually operated.
grand master key When a series of locks is divided into two or more sub-suites the key which controls all the sub-suites (i.e. all the locks in the entire complex) is called the grand master key.
great grand master key One higher in degree than a grand master key. It is used only in very special arrangements of master keyed locks.
grooves Long narrow milled out areas along the sides of the blade to allow the blade to bypass the wards in the keyway.
guards A guard is a fixed part inside a lock to prevent false keys from turning, or to prevent an instrument from reaching the bolt or levers.
gunmetal Another term for bronze.
hasp A hinged metal strap designed to be passed over a staple and secured in place.
hasp and staple A fastening in two pieces for a door or box to be secured by a padlock. The hinged part is called the hasp and shuts over the staple. For real security it is essential to use a hasp and staple with concealed fixing.
heel & toe locking Describes a padlock which has locking dogs at both the heel and toe of the shackle.
heel (of a padlock shackle) The part of a padlock shackle which is retained in the case when in the unlocked position.
hinge bolts Fixed steel protrusions fitted into the rear edge or hinge side of doors, closing into holes cut into the door frame, to protect from forced attack on the hinge side of the door.
hold back stop A thumb slide on the case of a cylinder rim nightlatch or in the forend of a cylinder mortice lock used either to hold back or alternatively deadlock the main bolt.
hollow post key A key with a bit projecting from a hollow cylindrical shaft.
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.
hookward key The ward is fixed in the lock case formed as part of a circle like a wheel ward, but with a return or flange so that a cut in the key to fit would be L shape.
horizontal lock A mortice or rim lock having the follower hole further from the forend than the keyhole, but in the same horizontal plane. Used when knob furniture is specified to prevent the barking of knuckles on the door frame.
Locksmith Terms Glossary i-l
imitation bma: An electro deposited powder or lacquer finish on metal to simulate as nearly as possible the genuine Bronze Metal Antique finish. It is known as lBMA.
impressioning:A means of fitting a key directly to a locked cylinder by manipulating a blank in the keyway and cutting the blank where the tumlbers have made marks.
interconnected lockset: A lockset whose trim provides a means of simultaneous retraction of two or more bolts which may also be operated independently.
jamb: The inside vertical face of a doorway.
keep or keeper: A term sometimes used, particularly in the North, for a staple or striking plate.
key change: A term sometimes used instead of “differ”. The change or differ of the key is generally indicated by number, and sometimes numbers and letters marked an the bow.
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.
key steps or key depths: This term usually means the bolt step and lever steps of a key for a lever lock.
keyway: The part of the plug where you insert the key.
keyway grooves: Long narrow milled out areas along the sides of the blade to allow the blade to bypass the wards in the keyway.
latch:A mechanical device which automatically keeps a door closed until a deliberate action is used to retract it.
latchset:A latch complete with necessary furniture including a spindle, ready for fixing to the door.
lever handle:A piece of lock or latch furniture, usually on a rose or plate, for use as an alternative to a knob for operating the springbolt of a lock or latch. All British lever handles are spring-loaded to ensure the return to horizontal after use.
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.
lever mechanism:A lock mechanism having, as its principle feature, one or more levers.
lever pack:A set of lever tumblers.
lever pivot:The stump in a lock on which the levers swing.
lever tumbler:Usually a flat, spring-loaded tumbler which pivots on a post.
link plate:The complementary member of box, desk and other locks which is fixed to the lid or some part of a cabinet, for example, and has one or more projecting links to enter the lock and engage the bolt.
lip (of striking plate):The projection on one side of a striking plate on the surface of which the springbolt of the lock or latch first strikes when the door is closed.
lock:Any device which prevents access or use by requiring special knowledge or equipment.
lockable bolt:A bolt that can be shot and locked in position by the use of a removable key.
locking latch:A latch with a bevelled springbolt or roller bolt which is capable of being lacked or secured, usually by key.
lockset:A lock complete with necessary furniture including a spindle, ready for fixing to the door.
locksmith:A person with the knowledge and ability to select, install, service and bypass all the components of an electrical or mechanical lock.
London strip:A steel bar fitted to the inside face of a door frame, shaped to accommodate the staple or striker of a rim latch lock.
long shackle (LS):A padlock shackle with a greater amount of clearance than the normal standard shackle.
lower pins:The pins of a lock that contact the cuts on the key. Also called bottom pins.
lubrication:On no account should oil be used to lubricate pin-tumbler cylinders. Graphite is the conventional lubricant for this mechanism.
Locksmith Terms Glossary M-P
master key A key which will open every lock in the master keyed suite.
master keyed (locks or latches) A lock or latch capable of being operated also by a master key as well as its own change or servant key.
master pins Small pins sometimes called wafers to build up chamber pin loading in pin tumbler master keyed cylinders.
mechanism (of locks or latches) The arrangement of the component parts and the manner in which they perform to achieve the required security and differing when operated by its key.
mortise A hole cut into the thickness of one edge of a door to receive a mortice lock or latch.
mortice lock (or latch) A lock or latch which is morticed to let into the thickness of the door from the meeting edge and held in position by screws through the forend.
narrow case lock or latch A rim lock or latch, the case of which is made specially narrow, usually less than three inches wide, for fixing to the narrow stile of a panelled or flush door.
nightlatch A rim or mortice latch with a bevelled springbolt or roller bolt which shoots when the door is closed, but can be withdrawn by key from outside and by knob or lever handle from inside.
nozzle A circular boss or ferrule containing the keyhole on some cabinet locks, including locker locks. Correctly relating to lever cabinet locks.
one-sided lock (single-entry) A lock which has a keyhole on one side only.
one-way action An action where the follower will turn only one way.
panThe removable mechanism chamber attached to the inside face of a safe door.
panel grilles Steel grilles made to size with various infills of expanded diamond mesh, square weldmesh or fancy infills, usually fitted internally.
peg ward A combination of wards resembling a sash ward but fixed by pegs to the lock case.
pins Usually the lower of each pair of tumblers in the pin tumbler cylinder mechanism. The upper are known as drivers.
pin stack The combination of a lower pin sitting beneath an upper pin. In master keyed locks, additional master pins may be located between the lower and upper pins.
pin tumbler mechanism The mechanism incorporated in the cylinder or body of a cylinder pin tumbler lock, latch or padlock.
pipe key A key with a flat bit and a hollow circular shank to locate on the drillpin. Used only on one-sided locks.
plug The part of the lock that you put the key into, and which turns to operate the lock.
pre-assembled lockset A lock designed to be installed into a cutout in the edge of a door. The lock body and most or all of its trim need no further assembly other than securing it to the door.
Locksmith Terms Glossary Q-T
rack bolt A bolt, usually a door bolt, which is toothed so that it may be operated by a pinion.
radiused forend A lock forend which is shaped radically, for use on one of a pair of swing doors.
rebate The measurement of the stepped reduction or recess in theforend of a rebated lock.
rebated (lock or latch) A morticelock or latch with a forend specially shaped to correspond with the shaped meeting edge of the door for which it is intended. See “Full Rebated”.
release A striker in Various forms to replace the lock strike and is operated electronically.
relocker A locking mechanism independent of any key operations, mounted remotely within a safe mechanism so as to relock the boltwork under certain forced attacks.
repeat differs That supply of differs which have been issued previously. This is usually associated with master keyed suites and where a replacement lock is required to have the same differ as the original.
reversed bolt (RB) A springbolt which has been turned round in its case to suit a door opening outwards instead of inwards. Great care should be taken to use this term RB only when ordering items which are required with the springbolt reversed.
rigid grilles Heavy duty, welded construction, rod or bar grilles, usually fitted externally or internally to the fabric of a building.
rim cylinder This relates to a pack which usually comprises the cylinder with plug, rose, connecting bar, two connecting screws and two keys.
rim lock A lock or latch typically mounted on the surface of a door or drawer.
roller bolt A springbolt made in the form of a roller, instead of being bevelled. It is recommended far more silent and easier closing of a door.
rose (1. A cylinder rose or ring in cylinder locks or latches.
(2. In door furniture, it is the small plate to which the lever handle or knob is affixed and which is screwed to the door surface.
safe lock A general term for the many varieties of key operated and other locks for safes.
sash lock An upright mortice lock, consisting of a latch bolt and a key operated bolt.
sash ward Used in rim and mortic elocks, alone or in conjunction with levels for the purpose of obtaining or increasing the differs.
servant key The change key of one (or more than one if of the same change) lock in a master keyed or grand master keyed suite.
set screw One which tightens or fastens another part after assembly or adjustment.
scotch spring lock A two-bolt rim lock with the reversible springbolt above or below the horizontal plane of the follower.
shackle The part of a padlock which passes through an opening in an object or fits around an object and is ultimately locked into the case.
shank(of key) The part of a pin or pipe key between the bow and the end, excluding the blade.
shear line The dividing line between the plug and the shell (the height to which the tops of the lower pins must be raised to open the lock).
shell The outer part of the lock that surrounds the plug.
shoot (of bolt) The distance a springbolt moves under the action of its spring.
shoulder(or bow stop) The edge of the key that touches the face of the lock to define how far the key is inserted into the lock.
side bar This is in addition to the existing pin or disc mechanism, and is a bar usually along the length of the mechanism and does not allow rotation until the mechanism is correctly lifted and can be directly controlled by the key.
side wards Notches cut into the sides of bitted keys so fashioned to enable the key to turn.
single-acting lever tumbler A lever tumbler which must be moved a minimum distance to allow travel of a bolt, but cannot be moved so far as to restrict travel of the bolt.
skeleton key Any non-cylinder key whose bit, blade, and/or post is cut away enough to allow it to enter and turn in locks with different ward arrangements. There is no universal skeleton key. Skeleton keys cannot be made for lever and cylinder lock mechanisms.
sliding grilles Steel sliding grille gates in single or double leaf, running on top and bottom guide tracks, locked by padlock or integral lock.
sliding lever A Lever which slides between or on guides instead of swinging on a pivot.
spacer A distance piece of thin metal placed between the levers of some locks.
spacing The term used to describe the horizontal distances across a key blade or bit.
spindle That part of the door furniture usually of square section which passes through the follower hole and is fitted to the knob(s) or lever handle(s) to operate the springbolt.
spiral spring A spring made of wire to approximately V shape like a feather spring; with one or more coils formed at the apex of the V to fit over a stump in the lock case.
spool pin A pin that has a groove cut around it’s periphery. The groove is intended to catch at the shear line as a deterrent to picking.
spoon The flattened end of a padlock shackle containing the bolt hole or slot which the bolt enters.
spring-loaded Moved under the control of, or against the pull of, a spring fixed at one end.
spring shackle padlock A padlock, the shackle of which springs open when unlocked, and is locked by snapping to.
springbolt Sometimes called the latchbolt. A bolt having the outer edge shaped by bevelling of the vertical face. It is a bolt which may be pushed back into the lock-case and will return to the extended position without mechanical assistance.
springlatch A latch with one bevelled springbolt which locks the door when shut. It is opened by key from the outside and by knob from inside.
steel lining Steel sheet linings applied to external or both faces of a door, usually screwed and bolted through.
stile A vertical member of a door.
stop knob (snib) A device incorporated in some latches and locking latches to hold the bolt retracted or deadlock the bolt when door is closed.
stop button(s) There are generally two in number. They are incorporated in the forend of certain cylinder mortice nightlatches or locks. One button, when depressed, renders the outside furniture inoperable and the other, when depressed, restores the power of operation. They are useful for privacy and on vestibule doors. They are sometimes referred to as “stopworks”.
straight cabinet lock A cabinet lock, with no flange on the case, for flush fitting to cupboards and drawers.
striking plate Sometimes referred to as a “striker”. It is a shaped flat metal plate fixed to the door frame or jamb with one or more bolt holes into which the bait or bolts shoot. There is a shaped projecting lip on one side to guide the springbolt., It is used with all mortice locks or latches, and with rim locks or latches with reversed springbalt on an outward opening door.
sub grand master key A key which will operate all locks in its own main group or (sub-grand suite) of a grand master keyed system.
sub master key A key which will operate all locks in its own smaller group (or sub-suite) of a grand master keyed system.
suite (of locks) A group or collection locks and/or locking latches and padlocks of different types and changes incorporated together under a master key or grand master key.
talon The gap that is formed by two curves to the radius of the bolt step of the key in a deadbolt lathe or runner of a lever lock where the key engages the bolt.
throw The distance a deadbolt moves under the action of its key.
thumb turn A small fitting, on the inside of a mortice lock, which is gripped between thumb and finger to operate the deadbolt. It should not be used on glass-or wood-panelled doors.
till lock A drawer lock, or more correctly a cabinet lock, having a springbolt that shoots upwards and a vertical keyhole. It is self-closing and is unlocked by key.
time lock A clockwork or electric timing device which disallows operation of a lock or the opening of a door on safes or strongrooms.
tip The very end of part of the key that you stick into the lock first.
toe (of a shackle) That part of the shackle which may be removed from the padlock body.
top master key The highest level masterkey that fits all the locks in a multi-level masterkeyed system.
top pins The pins in a lock that sit on top of the pin stack.
tubular key cylinder A cylinder whose tumblers are arranged in a circle and which is operated by a tubular key.
tubular lockset A bored lockset whose latch or bolt locking mechanism is contained in the component installed into the edge bore.
tumbler A movable detainer which must be lifted before the bolt of a lock can move.