Whether you are an amateur just looking to buy locks for your new home, or a budding professional in the field of locksmithing, there is some basic terminology, some local lingo that you need to know, which will be helpful for you in progressing towards your goal. Locksmithing is an ancient trade and craft, and hence has a rich vocabulary, which would be handy for anyone to know, before going to negotiate with a locksmith. Some words common to the locksmith jargon would be:
Key-Locks: Basic kind of locks which are operated with the use of keys.
Combination Locks: In contrast to key locks, combination locks require the use of an assigned sequence of numbers to be operated, instead of the use of keys. The combination of numbers can be entered on a keypad or dialed on a rotation dial depending on the lock.
Bow of the Key: It is the segment of the key which is not fitted into the lock. It is the part which you hold on to. Often it also has some useful information printed on it, such as a company name or a code. It is best to have this information noted down somewhere in case of a loss. In such situation the noted down code number can be presented along with some proof of ownership, and be used to have a new copy made of the misplaced key.
Key Blade: The part of the key which is inserted in the keyhole, and which operates the lock, is referred to as the key blade.
Tumblers: These are the parts inside the lock which need to be aligned for the lock to open. In key locks this is done by turning of the key, while in combination locks the task is accomplished by entering the correct combination.
Keyway: The pattern of grooves and millings along the side of the part of the key which is inserted into a lock is called the keyway. The keyway of the key should be compatible with the lock for it to turn the tumblers and operate the lock.
Master-Keyed: A group of locks, in which each lock is operated by its own individual key, but also can be operated by a master key which can access each lock in the group. This means that all locks in the group should have keyways which match with those of the master key.
Keyed-Different/ Keyed-Alike: When different locks in a group of locks are operated by different keys, it is termed as being keyed-different. Whereas, if a group of locks can be opened by the same singular key it is referred to as being keyed-alike.
Lost Keys: I guess the term already spells out its meaning. But for the sake of protocol, a lost key is any key belonging to a lock, which you have misplaced and is no longer in your possession. It may have been lost in a place you know, or you may have misplaced it without knowing where exactly, you lost it. In such a situation, it is best to have spares available to access the lock, and then to have those locks rekeyed, in order to avoid theft or break-in.
Rekeying: Rekeying is the process of replacing the tumblers inside the cylinder of a lock with tumblers of different size. Such a lock then requires a new set of keys and no longer can be operated by the old set. Rekeying is usually done in case of a loss of keys, or them falling into the wrong hand.