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" Map the Author's Attitude Before Reading Questions Force Contrast Between Two Similar Words Stop Skipping Words and Read the Tone 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