Plumber
late Middle English (originally denoting a person dealing in and working with lead): from Old French plommier, from Latin plumbarius, from plumbum ‘lead’.
wiktionary
From Middle English plumber, from Old French plummier (French plombier); from Latin plumbārius, from plumbum(“lead or lead shot”).
etymonline
plumber (n.)
late 14c. (from c. 1100 as a surname), "a worker in any sort of lead" (roofs, gutters, pipes), from Old French plomier "lead-smelter" (Modern French plombier) and directly from Latin plumbarius "worker in lead," noun use of adjective meaning "pertaining to lead," from plumbum "lead" (see plumb (n.)). The meaning focused 19c. on "workman who installs pipes and fittings" as lead pipes for conveying water and gas became the principal concern of the trade.
In U.S. history, in the Nixon administration (1969-74), it was the name of a special unit for investigation of "leaks" of government secrets.
