One who works in or with lead.

A plumber is someone who installs, repairs, and maintains pipes and other equipment for water, gas, and drainage systems.

A person who investigates or prevents leaks of information.

(Britain, informal) In the Royal Navy, an apprentice, a boy aged 16 to 18, who is trained in technical skills at the Dockyard Schools to become an artificer.

(medicine, slang) A urologist.