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plumb

[pluhm]
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noun
  1. a small mass 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.Compare plumb line.
adjective Also plum.
  1. true according to a plumb line perpendicular.
  2. Informal. downright or absolute.
adverb Also plum.
  1. in a perpendicular or vertical direction.
  2. exactly, precisely, or directly.
  3. Informal. completely or absolutely: She was plumb mad. You're plumb right.
verb (used with object)
  1. to test or adjust by a plumb line.
  2. to make vertical.
  3. Shipbuilding. horn(def 32).
  4. to sound with or as with a plumb line.
  5. to measure (depth) by sounding.
  6. to examine closely in order to discover or understand: to plumb someone's thoughts.
  7. to seal with lead.
  8. to weight with lead.
  9. to provide (a house, building, apartment, etc.) with plumbing.
verb (used without object)
  1. to work as a plumber.
Idioms
  1. out of/off plumb, not corresponding to the perpendicular; out of true.

Origin of plumb

1250–1300; Middle English plumbe, probably < Anglo-French *plombe < Vulgar Latin *plumba, for Latin plumbum lead
Related formsplumb·a·ble, adjectiveplumb·less, adjectiveplumb·ness, nounre·plumb, verb (used with object)un·plumb, adjective
Can be confusedplum plumb

Synonyms

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2. vertical, straight, square.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
British Dictionary definitions for unplumb

plumb

noun
  1. a weight, usually of lead, suspended at the end of a line and used to determine water depth or verticality
  2. the perpendicular position of a freely suspended plumb line (esp in the phrases out of plumb, off plumb)
adjective Also: plum
  1. (prenominal) informal, mainly US (intensifier)a plumb nuisance
adverb Also: plum
  1. in a vertical or perpendicular line
  2. informal, mainly US (intensifier)plumb stupid
  3. informal exactly; precisely (also in the phrase plumb on)
verb
  1. (tr often foll by up) to test the alignment of or adjust to the vertical with a plumb line
  2. (tr) to undergo or experience (the worst extremes of misery, sadness, etc)to plumb the depths of despair
  3. (tr) to understand or master (something obscure)to plumb a mystery
  4. to connect or join (a device such as a tap) to a water pipe or drainage system
Derived Formsplumbable, adjective

Word Origin

C13: from Old French plomb (unattested) lead line, from Old French plon lead, from Latin plumbum lead
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for unplumb

plumb

n.

"lead hung on a string to show the vertical line," early 14c., from Old French *plombe, plomee "sounding lead," and directly from Late Latin *plumba, originally plural of Latin plumbum "lead (the metal), lead ball; pipe; pencil," a word of unknown origin, related to Greek molybdos "lead" (dialectal bolimos) and perhaps from an extinct Mediterranean language, perhaps Iberian.

plumb

v.

early 15c., "to sink" (like lead), from plumb (n.). Meaning "take soundings with a plumb" is first recorded 1560s; figurative sense of "to get to the bottom of" is from 1590s. Related: Plumbed; plumbing.

plumb

adj.

"perpendicular, vertical," mid-15c., from plumb (n.). The notion of "exact measurement" led to extended sense of "completely, downright" (1748), sometimes spelled plump, plum, or plunk.

Online Etymology Dictionary, © 2010 Douglas Harper