from The Century Dictionary.
- noun A bolt so constructed as to drop into a socket.
- noun The bolt which keeps the drop of a gallows in place until the signal for its withdrawal is given.
Sorry, no etymologies found.
There was a drop-bolt to the door, which, upon trying to open, she found was down; and she felt so frightened and so fully persuaded her dear mistress was dead, that she stood for a minute and cryed; but recollecting herself, she called for help, and ran down to the rest of the servants with her alarming account, and they returning with her, the door was instantly forced open, and the room found empty.