Plumb, v. t. [imp. & p. p.Plumbed (plŭmd); p. pr. & vb. n.Plumbing (plŭm″ĭng).] 1. To adjust by a plumb line; to cause to be perpendicular; as, to plumb a building or a wall.
2. To sound with a plumb or plummet, as the depth of water; hence, to examine by test; to ascertain the depth, quality, dimension, etc.; to sound; to fathom; to test.
He did not attempt to plumb his intellect. Ld. Lytton.
3. To seal with lead; as, to plumb a drainpipe.
4. To supply, as a building, with a system of plumbing.