An Etymological Dictionary of Astronomy and Astrophysics

A small mass of lead or other heavy material, as that suspended by a line and used to measure the depth of water or to ascertain a vertical line (Dictionary.com). → plumb line.

Etymology (EN): M.E. plumbe, from O.Fr. *plombe, plomee “sounding lead,” from L. plumbum “lead (the metal), lead ball,” of unknown origin, related to Gk. molybdos “lead.”

Etymology (PE): Gulé “ball, sphere,” a variant of golulé, → bullet.