Lewis & Short

plumbārĭus, a, um, adj. [plumbum], of or belonging to lead, lead-: artifices plumbarii, workers in lead, plumbers, Vitr. 8, 7: officinae, plumbers’ shops, Plin. 34, 18, 54, § 175: metallum, a lead-mine, id. 33, 7, 40, § 119.
Subst.

  1. A. plumbārĭus, ii, m. (sc. artifex), a plumber; plur., Dig. 50, 6, 6.
  2. B. plumbārĭum, ii, n., a place to keep leaden vessels in: plumbum, plumbeus, plumbarium, Not. Tir. p. 164.