[plumb] n [ME, fr. (assumed) OF plomb lead, fr. L plumbum] (14c): a lead weight attached to a line and used to indicate a vertical direction -- out of plumb or off plumb : out of vertical or true
[2]plumb adv (15c) 1: straight down or up: vertically
2. chiefly dial: to a complete degree: absolutely "'you're ~ crazy', she remarked, with easy candor --Harper's Weekly"
3: in a direct manner: exactly; also: without interval of time: immediately [3]plumb vt (15c) 1: to weight with lead
2. a: to measure the depth of with a plumb b: to examine minutely and critically "~ing the book's complexities"
3: to adjust or test by a plumb line
4: to seal with lead
5. [back-formation fr. plumber]: to supply with or install as plumbing ~ vi: to work as a plumber [4]plumb adj (15c) 1: exactly vertical or true
2: thorough, complete syn see vertical