(from the article `hand tool`) A plumb line is a light line with a weight (plumb bob) at one end that, when suspended next to a workpiece, defines a vertical line. `Plumb` comes ... Found on http://www.britannica.com/eb/a-z/p/81
noun a cord from which a metal weight is suspended pointing directly to the earth`s center of gravity; used to determine the vertical from a given point Found on https://www.encyclo.co.uk/local/20974