Etymology
Advertisement

plumb (n.)

early 14c., "a mass of lead hung on a string to show the vertical line" (mid-14c. as "the metal lead"), 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; Beekes and de Vaan say it probably is unrelated to Greek molybdos "lead" (dialectal bolimos). It is perhaps a loan-word from an extinct language of the western Mediterranean (based on similarities of words in Berber and Basque). The -b was restored in English after c. 1400. Plumb-rule is attested from c. 1400.

plumb (v.)

late 14c., plumben, "to sink" (like lead); mid-15c., "weight (a fishing line)," from plumb (n.). Meaning "take soundings with a plumb" is recorded from 1560s; the figurative sense of "to get to the bottom of" is from 1590s. The meaning "to work as a plumber" is by 1889. Related: Plumbed; plumbing.

plumb (adj.)

"perpendicular, vertical, true according to a plumb-line," mid-15c., plom, from plumb (n.). As an adverb, "in a vertical direction, straight down," c. 1400. The notion of "exact measurement" led to the extended adverbial sense of "completely, downright" (1748), sometimes spelled plump, plum, or plunk.

Advertisement
Advertisement
Definitions of plumb
1
plumb (v.)
measure the depth of something;
plumb (v.)
weight with lead;
plumb (v.)
examine thoroughly and in great depth;
plumb (v.)
adjust with a plumb line so as to make vertical;
2
plumb (adv.)
conforming to the direction of a plumb line;
plumb (adv.)
exactly;
fell plumb in the middle of the puddle
Synonyms: plum
plumb (adv.)
completely; used as intensifiers;
I'm plumb (or plum) tuckered out
Synonyms: clean / plum
3
plumb (n.)
the metal bob of a plumb line;
Synonyms: plumb bob / plummet
4
plumb (adj.)
exactly vertical;
the tower of Pisa is far out of plumb
From wordnet.princeton.edu