lockman

noun4

1. •
   A man who operates a lock on a waterway.

   • A lockman while attempting to jump on board the steamer "St. Francis," missed his footing and fell into the canal. — 1879
2. •
   A criminal who is skilled at picking locks and disabling alarm systems.

   • The other thing is, a lockman. We need somebody really good, to follow the schematics I got and shut down all the alarms without kicking them on instead. — 2011
3. •
   An officer who acts as a kind of undersheriff to the governor.

   • the defendent must be summoned by the Coronor or his deputy (a lockman) to appear at the next court day, when the action is called in rotation. — 1860
4. •
   (Scotland, no longer used) A public executioner.

   • In 1780 James Alexander, lockman of Edinburgh, was by the city chamberlain paid for service at an execution 13s. 4d., with a fee of 2s. 6d. for the use of his rope. — 1884