Dead bolt is a common term for a locking mechanism used in doors. Despite its practical purpose, there are several synonyms that can be used to describe it. One term that is commonly used interchangeably with dead bolt is "deadlock." A deadlock is a type of lock that can only be opened with a key and cannot be disengaged from the outside. Another synonym for dead bolt is "mortise lock," which is a type of lock that is embedded or flush with the door. A third synonym is "latch bolt," which is a type of dead bolt that is operated by turning a knob or lever on the inside of the door. Regardless of the synonym used, the purpose of the dead bolt remains the same - to provide strong and secure locking for doors.