The following Glossary of Locksmith Terminology is provided courtesy of the Master Locksmith Association (MLA). Click on a letter below to be taken to its corresponding terms.

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.

Throating - The space between the collar and the nearer edge of the bit of two side keys.



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.

Tie bars - The horizontal members of a vertical bar grille.

Time Lock - A clockwork or electric timing device which disallows operation of a lock or the opening of a door on safes or strongrooms.

Toe - The extreme tip of a bitted key.

Tubular mortice lock or latch - A lock or latch so designed that the case is tubular in form. The fitting of this type of latch requires only the drilling of a round hole into the edge of the door into which the lock or latch is fitted, and secured in position by screws in the forend. It is very economical in fitting time.

Tumbler - A movable detainer which must be lifted before the bolt of a lock can move.

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