SAT GRE plumb Definition Straight down or vertical; also, to measure the depth of something. Example "The arrow fell plumb to the ground." Sign in to save SAT Quiz → GRE Quiz → ← plumage plumber → Study tips featuring "plumb" Let the Argument Reveal Unfamiliar Word Meanings Group Words Together by Emotional Tone Map the Author's Attitude Before Reading Questions Related words SAT antonym SAT abase SAT abdicate SAT abdomen SAT abduction SAT abet SAT abeyance SAT abject SAT abjure SAT ablution SAT abnegate SAT abnormal