curber

noun

1. Someone or something which curbs.

   “[T]hey required him as a safeguard against the demon and a curber of other people's crimes.”

2. (historical, slang)A type of thief who used a ‘curb’ or hooked pole to steal things through open windows.

   “Night was the natural time for the curber’s activities and striking up an acquaintance with a serving maid was an invaluable way of getting a window left open or learning the exact layout of the rooms in the house.”