What is the meaning of plumb?

noun

• The metal bob of a plumb line.
  • synonyms: plumb bob, plummet

verb

• Measure the depth of something.
• Weight with lead.
• Examine thoroughly and in great depth.
• Adjust with a plumb line so as to make vertical.

adjective

• Exactly vertical.
  • usage: "the tower of Pisa is far out of plumb"

adverb

• Completely; used as intensifiers.
  • usage: "clean forgot the appointment"; "I'm plumb (or plum) tuckered out"
  • synonyms: clean, plum
• Conforming to the direction of a plumb line.
• Exactly.
  • usage: "fell plumb in the middle of the puddle"
  • synonyms: plum