A skeleton key (or passkey) is a very simple design of key that usually has a cylindrical shaft (sometimes called a shank) and a single, minimal flat, rectangular tooth or bit. Skeleton keys can be made out of many metals including popular Cast Iron Keys, Copper Keys or Brass Keys. Skeleton keys are also usually distinguished by their bow, or the part one would grasp when inserting the key, which can be either very plain or extremely ornate. A skeleton key is designed to circumvent the wards in warded locks. Warded locks and their keys provide minimal security and only a slight deterrent as any key with a shaft and tooth that has the same or smaller dimensions will open the lock. However, warded keys were designed to only fit a matching lock and the skeleton key would often fit many. Many other objects that can fit into the lock may also be able to open it.
Due to its limited usefulness, this type of lock fell out of use after more complicated types became easier to manufacture. In modern usage, the term “skeleton key” is often misapplied to ordinary bit keys and barrel keys, rather than the correct definition: a key, usually with minimal features, which can open all or most of a type of badly designed lock. Bit keys and barrel keys can be newly-minted (and sold by restoration hardware companies) or antique stores.
They were most popular in the late 1800s, although they continued to be used well into the 20th century and can still be found today in use, albeit in vintage homes and antique furniture.
