What type of lock is a mortise lock?

A mortise lock is indeed characterized as a type that is fitted into a pre-drilled opening inside a door, which aligns with the description provided. This type of lock is made to fit into a pocket - or a mortise - that is cut into the edge of the door. The design allows it to integrate more securely with the door compared to surface-mounted locks, as it is recessed into the door itself. This results in a cleaner appearance, enhances security, and allows for the use of more complex locking mechanisms often found in mortise locks.

Furthermore, mortise locks can come with various functionalities, such as being able to accommodate deadbolts and are compatible with multiple locking options, making them a popular choice in both residential and commercial settings. Understanding this design helps in recognizing the unique advantages and applications of mortise locks in fire safety and security scenarios.