- A lever that closes or tightens a hatch or door.
As early as the 15th century.
When this word began to pertain to ships is uncertain, but it’s speculated to have been sometime in the 16th century. There are many different types of dogs with different applications since it’s also a term used in the engineering field. According to Wikipedia, the term dog refers to how a dog (the animal) will bite down and hold on to something. Aboard ships, dogs can be operated in a variety of ways depending on how the door/hatch operates. On some doors, each dog needs to be manually operated, and on others, it can be automatic when the door is shut.
Rogers, J.G. (1985). Origins of Sea Terms. Mystic Seaport.