[plumb line] n (15c) 1: a line (as of cord) that has at one end a weight (as a plumb bob) and is used esp. to determine verticality
2: a line directed to the center of gravity of the earth: a vertical line
[plumb line] n (15c) 1: a line (as of cord) that has at one end a weight (as a plumb bob) and is used esp. to determine verticality
2: a line directed to the center of gravity of the earth: a vertical line
Merriam-Webster English vocab. Английский словарь Merriam Webster. 2012