1. (n.)plumb a smallmass of lead or other heavy material, as that suspended by a line and used to measure the depth of water or to ascertain a vertical line.
9. (adverb)plumb, plum exactly "fell plumb in the middle of the puddle"
Definition of 'plumb'
Webster Dictionary
1. (adj)plumb perpendicular; vertical; conforming the direction of a line attached to a plumb; as, the wall is plumb
2. (adverb)plumb in a plumb direction; perpendicularly
3. (noun)plumb a littlemass or weight of lead, or the like, attached to a line, and used by builders, etc., to indicate a vertical direction; a plummet; a plumbbob. See Plumb line, below
5. (verb)plumb 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