Why a few words make a phone call easier
Lock talk can sound like a foreign language. Someone mentions the keyway, the bitting, the shear line and the plug, and you nod politely while wondering what any of it means. Yet these words describe things you can see and touch on every key you own.
Knowing a handful of terms helps in practical ways. You can describe a problem more clearly on the phone. You can understand why a copy cut from a worn key does not work. You can follow an explanation of why a lock was rekeyed rather than replaced. And you can read a package label without feeling lost.
This glossary is arranged by the part of the key or lock you are looking at, starting with the key, moving into the cylinder, and ending with the terms that describe systems of keys. It is not a technical manual. It is a friendly map.
Where a term deserves more depth, we point you to a longer page, such as how a pin tumbler lock works in plain words.
The parts of a key you can see
The bow is the head of the key, the part you grip and turn. It may be round, square, rubber covered or decorative, and it often carries a brand name or a stamped code. The bow does no security work. It is simply the handle, which is why a key with a fancy bow is not necessarily more secure than a plain one.
The blade is the long part that goes into the lock. Along one or both edges you will see the cuts. Along the sides of the blade you will see grooves or ridges, which are part of the keyway profile, discussed below. The tip is the end of the blade, and the shoulder is the flat stop near the bow that decides how deep the key sits in the lock.
The shoulder matters more than most people realize. On many keys it sets how far the blade enters the lock, so that the cuts line up with the pins at the right place. Some keys stop at the tip instead, and a copy must match whichever style the original uses. A copy cut a fraction too deep or too shallow may feel almost right and still fail.
A key blank is an uncut key. Blanks come in many shapes, and the right one must match the keyway. Our page on key blank types and why copies fail shows why a blank that looks similar can still be wrong.
Tell the dispatcher the Orlando area, what happened and what you are standing in front of, whether a door, a vehicle or a gate.
CallKeyway: the shape of the opening
The keyway is the shaped slot in the front of the lock where the key goes. Think of it as the outline. The ridges and grooves running along a key blade must match the shape of the keyway so that the key can enter at all. If the profile is wrong, the key will not slide in, no matter how well the cuts are made.
Many manufacturers use their own keyway shapes, and each shape has a name or a code. Common household locks use shapes that many brands share, which is why a key from one store can often be cut from a blank sold by another. More specialized or restricted keyways limit who can obtain blanks, which is why they are used in some businesses and buildings. Our guide on restricted keyways and why they matter goes deeper.
A keyway does not make a lock secure by itself. It narrows which keys can enter, but the real security comes from the way the cylinder inside responds to the cuts. Still, a more complicated profile can make casual copying harder, and a lock can usually be fitted with a different keyway when the cylinder is replaced.
When a locksmith asks you for the brand and keyway of a lock, they are trying to work out which blank to use. If you do not know, they can often read it from the key itself or from the cylinder.
Read the sections in any order, and come back to the ones you need. Nobody has to memorize the whole list to feel more confident at the counter or on the phone.
Bitting: the pattern of cuts
Bitting is the pattern of cuts along the blade. Each cut has a depth, and the series of depths is what makes one key different from another. When people say a key is cut to a code, they mean the bitting follows a list of depth numbers.
Each position along the blade corresponds to a pin inside the lock. The depth of the cut at that position pushes the pin to a certain height. When all the pins sit at the right height, the lock can turn. A different bitting pushes the pins to different heights, and the lock stays closed.
A key with five cuts and several possible depths per cut can form many different combinations. This is why a household has many unique keys, and why a key from your neighbor will not open your door. It is also why a worn key causes trouble: if the cuts are rounded off, the pins no longer sit at the exact height, and the lock may stick.
Bitting is not the same as the keyway. The keyway is the outline, the bitting is the detail within it. A thousand keys can share one keyway and each have different bitting. Our article on key codes and duplicate keys explained shows how a code can describe the cuts.
A few words describe wear and trouble. Key wear is the gradual rounding of the cuts from use, and it is the most common reason a key becomes sticky. Binding describes a lock that resists turning because something inside is out of line. Gritty or gummy are everyday words locksmiths use for a lock whose pins are coated with dirt or old lubricant. If you can describe the feel of your lock with those words, you have given a useful clue.
Also worth knowing is the idea of a code cut key. Some keys are made from the numbers rather than from a physical sample. A locksmith with the right information can cut a new key without the original in hand, which is part of why they ask for proof that you are entitled to the lock. The code is a sensitive piece of information, and it deserves the same care as the key itself.
- Keyway is the shape of the slot and of the blade profile.
- Bitting is the pattern and depth of the cuts along the blade.
- A blank has the profile but not yet the cuts.
- A cut key has both the profile and the correct bitting for one particular lock.
Inside the cylinder: plug, pins and shear line
The cylinder is the working core of most locks. Inside it sits the plug, the round part that turns when the right key is inserted. Around the plug is the housing, which holds the plug in place. When the plug turns, it moves the bolt or latch, and the door unlocks.
In a pin tumbler lock, small stacks of pins sit in channels above the plug. Each stack has a driver pin and a key pin, pushed down by a spring. When the correct key is inserted, the cuts lift each stack so that the gap between the two pins lines up with the edge of the plug. That edge is called the shear line.
When all the gaps align with the shear line, the plug is able to rotate. When even one pin is out of place, the pin blocks the plug and the lock stays closed. That is the entire principle behind the common household lock, and it has served for a very long time.
Rekeying a lock means changing the pins so that a new bitting works and the old one does not. The plug and housing stay the same. Our service page on rekeying describes what happens in practice, and the explainer on how rekeying changes who can enter shows the effect for a household.
Terms for keys that open more than one lock
A change key is the ordinary key that opens one lock or one group of locks that have been keyed alike. Most people carry change keys all day without calling them that. A set of locks keyed alike means that a single key operates them all, which is handy when you want one key for the front and back doors.
A master key is a key that opens a group of locks that each also have their own change key. Offices, apartment buildings and some commercial properties use master key systems so that a manager can enter many doors while each tenant uses only their own. A control key is a special key used to remove and replace a core in some lock types. These terms are explained in more detail in master key terms.
A key control program, sometimes called key control, simply means keeping track of who holds which key. Writing a simple list of who holds what is the practical core of it, even for a small office.
The word keyed alternate or keyed different appears on packaging. Keyed alike means several locks open with the same key. Keyed different means each lock has its own key. Knowing the difference stops you from buying three locks and being surprised by three separate keys.
Words on lock labels and spec sheets
When you shop for locks, you may see words such as grade, backset, strike and bolt throw. The grade describes the durability and strength rating a manufacturer assigns under a standard test. Our guide on lock grades explained for homeowners unpacks what the numbers mean in general terms.
The backset is the distance from the edge of the door to the center of the hole drilled for the lock. The bolt throw is how far the bolt extends when locked. The strike is the metal plate on the frame where the bolt enters. These details decide whether a lock fits your door and how well it resists force, and we cover the fitting side in backset and door prep measurements.
Single cylinder and double cylinder are terms for deadbolts. A single cylinder deadbolt has a key on the outside and a thumb turn inside. A double cylinder has a key on both sides. The difference matters for safety in an emergency, and our guide on single cylinder or double cylinder deadbolt sets out the trade offs.
Finally, a label may say pick resistant. We explain that phrase in what pick resistant means on a lock label, since it means less than people sometimes assume.
Last, a note on the words used for the hardware around the lock. The latch is the spring loaded piece that holds a door shut on a passage set. The deadbolt is the heavier, manually thrown bolt that gives extra resistance. The faceplate is the metal edge plate at the side of the door, and the escutcheon is the decorative plate around a keyhole or handle. The thumb turn is the knob you twist from the inside to move a deadbolt. None of these changes the key, but all of them show up in a conversation about replacing a lock.
Humid air matters to all of this. In Central Florida, moisture can leave a film on pins and in keyways, and salt carried on the breeze can dull the finish of exposed hardware. If a key feels rough in the lock, that is worth mentioning when you call.
Terms for modern and automotive keys
A transponder key contains a small chip that talks to the vehicle. The metal blade turns the ignition or opens the door, and the chip confirms to the car that the key is genuine. If the chip is missing or not programmed, the engine may not start even though the blade fits. See transponder key basics.
A remote head key combines a blade with a remote control for locking and unlocking, built into one piece. A smart key, sometimes called a proximity key, lets the driver start the car by pressing a button while the key stays in a pocket. A key card is a flat credential used by some brands in place of a blade. Our page on smart keys, remote head keys and plain blades compares them.
A laser cut key, sometimes called a sidewinder or an internal cut key, has a groove milled into the flat of the blade rather than cuts on the edge. A dimple key has small round cavities drilled into its face. These designs resist casual copying and need special machines. Our article on laser cut keys and dimple keys explained covers the idea.
A VIN is the vehicle identification number, a unique code stamped on every car. Locksmiths ask for it because it helps identify the key type. Have it ready, along with the make, model and year, when you call.
Putting the words to work
Imagine you call about a front door lock that has stopped working smoothly. You can now say the key feels loose, the cuts look worn, and the lock has the same keyway as the other doors. That is a precise description that helps the locksmith decide whether a new key, a rekey or a cylinder replacement is likely to help.
Or imagine you want one key for three doors. You can ask whether the locks can be rekeyed alike, and the answer will be about the pins and the keyway, not about the doors. You can ask whether your current locks share a keyway, and the locksmith will know what you mean.
Or imagine you are a landlord who wants a master key. You can ask about a master key system and a control key, and you will understand the reply. The idea extends easily to larger buildings.
A good locksmith will not insist on jargon. They will explain the work and the price before starting, in whatever words suit you, and test the finished lock with you. The glossary is simply there so you are never at a loss for a term.
Questions people ask
What is the difference between a keyway and bitting?
The keyway is the shape of the slot and the matching profile of the key blade, which decides whether a key can enter the lock. The bitting is the pattern of cuts along the blade, which decides whether the lock will turn once the key is inside.
What is a shear line?
It is the imaginary line inside a pin tumbler lock where the plug meets the housing. When the correct key lifts every pin stack so the gaps line up at that line, the plug can rotate. If any pin sits wrong, the plug stays blocked.
Why do some copies of my key not work?
Common causes are the wrong blank, a copy cut from a worn key, or a cut that is a fraction off. Because the cuts must place each pin at an exact height, small errors matter. Having a copy made from the original, on the right blank, helps.
What does keyed alike mean?
It means two or more locks are set up to open with the same key. People choose it so they can use one key for the front and back doors. Keyed different means each lock has its own key. Photos of the door or lock make the conversation easier.
What is a master key?
A master key opens a group of locks that each also have their own individual key. Property managers and businesses use them so one person can enter many doors while tenants or staff only carry the key for their own. Details differ from home to home, so ask when unsure.
Do I need to know these terms to call a locksmith?
No. A good locksmith will explain the work and the price in plain words. Knowing a few terms simply helps you describe what you see and follow the explanation. Make, model, year and VIN matter more for car keys than any glossary word.