Also called plumb bob. a piece of lead or some other weight attached to a line, used for determining perpendicularity, for sounding, etc.; the bob of a plumb line.

something that weighs down or depresses.

to plunge.

verb

ascend , rise , shoot up

verb

collapse , crash , decline , decrease , descend , dip , dive , downturn , drop , drop down , dump , fall , nose-dive , plunge , precipitate , sink , skid , stoop , swoop , tumble , slump , buxom , chubby , fleshy , obese , plop , plumb , plunk , portly , rotund , stout , support