Plumb

Plumb (plŭm), n. [F. plomb, L. plumbum lead, a leaden ball or bullet; cf. Gr. μόλυβος, μόλιβος, μόλυβδος. Cf. Plummet, Plunge.] A little mass or weight of lead, or the like, attached to a line, and used by builders, etc., to indicate a vertical direction; a plummet; a plumb bob. See Plumb line, below.

Plumb bob. See Bob, 4. — Plumb joint, in sheet-metal work, a lap joint, fastened by solder. — Plumb level. See under Level. — Plumb line. (a) The cord by which a plumb bob is suspended; a plummet. (b) A line directed to the center of gravity of the earth. — Plumb rule, a narrow board with a plumb line, used by builders and carpenters.

Plumb, a. Perpendicular; vertical; conforming the direction of a line attached to a plumb; as, the wall is plumb.

Plumb, adv. In a plumb direction; perpendicularly. "Plumb down he falls." Milton.

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.